JP2001119069A - Nitride semiconductor light emitting element - Google Patents

Abstract

(57) [Problem] To provide a nitride semiconductor light emitting device having a high light emission output and a narrow half width of an emission spectrum. An active layer (15) has a quantum well structure. Among the p-type cladding layers 96 provided on the active layer (15), the first p-type cladding layer (96a) is formed of a p-type nitride semiconductor containing aluminum and gallium, and the second p-type cladding layer (96) is formed. 96b) is a similar p-type nitride semiconductor, but formed with a band gap larger than that of the first p-type cladding layer (96b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device such as a light emitting diode (LED) and a laser diode (LD), and more particularly, a semiconductor layer structure formed on a substrate is made of a nitride semiconductor. The present invention relates to a nitride semiconductor light emitting device and a light emitting device.

[0002]

2. Description of the Related Art Indium is used as a material for semiconductor light emitting devices such as LEDs and LDs that emit light in the wavelength region from the ultraviolet to the red.
Promising are nitride semiconductors such as GaN, AlGaN, and GaN. At present, blue LEDs and blue-green LEDs made of these nitride semiconductor materials have been put to practical use and used for displays, signals and the like.

[0003] These blue and blue-green light emitting nitride semiconductors L
The ED element has a double hetero structure, and basically has an n-type contact layer made of n-type GaN,
N-type cladding layer made of n-type AlGaN and n-type InGa
It has a structure in which an active layer made of N, a p-type clad layer made of p-type AlGaN, and a p-type contact layer made of p-type GaN are sequentially stacked. For the active layer, Si, G
A donor impurity such as e and / or an acceptor impurity such as Zn and Mg are doped. The emission wavelength of this LED element can be changed from the ultraviolet region to the red region by changing the ratio of In in InGaN constituting the active layer or by changing the type of impurities doped into the active layer.

On the other hand, various structures have conventionally been proposed for LD elements. For example, JP-A-6-21511
Japanese Patent Application Laid-Open Publication No. HEI 10-125605 discloses a separate confinement type LD element. In this LD device, an active layer made of InGaN and having a thickness of 100 Å or less is formed of an n-type GaN layer and a p-type Ga
N-type GaN layer and p-type G layer.
a p-type AlGaN layer and an n-type A
It has a structure provided with an lGaN layer. In this element,
The AlGaN layer functions as a light confinement layer.

[0005]

As for the nitride semiconductor LED device, the light emission output has been improved to a practical level by realizing the double hetero structure as described above. However, it is not only desirable that an LED element exhibit a higher emission output, but also in a conventional LED element, the active layer (light emitting layer) is doped with impurities, so that the half width of the emission spectrum is reduced. There is a tendency to be wide. If the half-width of the emission spectrum is wide, the emission color looks white, so when a full-color display is manufactured using such an LED element, for example, the color reproduction area of the color display is narrowed. Becomes

On the other hand, a nitride semiconductor LD element has a double hetero structure having an active layer formed of non-doped InGaN, as described in Japanese Patent Application Laid-Open No. Hei 6-21511. Although it is feasible, the LD element has not actually oscillated. In particular, as described in this publication, when the active layer has a quantum well structure, the light emission output should be greatly improved. However, as described above, laser oscillation does not actually occur.

Therefore, when the present invention is applied to an LED element, it is possible to realize an LED element having a high emission output and a narrow half-width of an emission spectrum. It is an object of the present invention to provide a nitride semiconductor light emitting device having a novel structure that can realize an LD device capable of performing the above.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on a nitride semiconductor light emitting device having a structure in which an active layer is sandwiched between a p-type semiconductor layer and an n-type semiconductor layer.
By forming the active layer from GaN and making it a quantum well structure (including both a single quantum well structure and a multiple quantum well structure), the light emission from the active layer can be based on the interband emission of InGaN. A nitride capable of providing high emission output and / or real laser oscillation by providing light emission with a narrow half-value width and providing a specific p-type layer or n-type layer in contact with the active layer It has been found that a semiconductor light emitting device can be obtained. Further research was conducted based on these findings, and the present invention was completed.

More specifically, according to a first aspect of the present invention, a quantum well having a first main surface and a second main surface and including a nitride semiconductor containing indium and gallium A semiconductor laminated structure having an active layer having a structure, an n-type nitride semiconductor layer provided on a first main surface of the active layer, and a p-type nitride semiconductor layer provided on a second main surface. The n-type nitride semiconductor layer includes a first n-type cladding layer provided in contact with a first main surface of the active layer and made of an n-type nitride semiconductor not containing aluminum; The n-type nitride semiconductor layer includes a second p-type cladding layer made of a p-type nitride semiconductor containing aluminum and gallium, and is formed at a position further away from the active layer than the first n-type cladding layer. Including an n-type contact layer made of n-type GaN. That the nitride semiconductor light emitting device is provided.

According to a second aspect of the present invention, the first aspect
An active layer having a quantum well structure including a nitride semiconductor containing indium and gallium, and an n-type nitride provided on the first main surface of the active layer. A semiconductor laminated structure having a p-type nitride semiconductor layer provided on a second main surface, the n-type nitride semiconductor layer being in contact with a first main surface of the active layer. Provided,
And a first n-type cladding layer made of an n-type nitride semiconductor not containing aluminum, wherein the p-type nitride semiconductor layer is made of a second p-type nitride semiconductor made of a p-type nitride semiconductor containing aluminum and gallium. A mold clad layer, and the second
And a p-type contact layer made of p-type GaN formed at a position farther from the active layer than the p-type cladding layer.

In the first or second aspect, the active layer and the first n-type cladding layer may have a total thickness of 300 Å or more. The n-type nitride semiconductor layer is formed at a position farther from the active layer than the first n-type clad layer, and is formed of an n-type nitride semiconductor containing aluminum and gallium. Layers may be further included. Further, the p-type nitride semiconductor layer includes a first p-type clad layer provided between the active layer and the second p-type clad layer and made of a p-type nitride semiconductor not containing aluminum. Can be.
Furthermore, the active layer, the first n-type cladding layer and the first p-type
The mold cladding layer can have a total thickness of 300 Å or more.

According to a third aspect of the present invention, there is provided an active layer having a quantum well structure having first and second main surfaces and including a nitride semiconductor containing indium and gallium. A semiconductor multilayer structure having an n-type nitride semiconductor layer provided on a first main surface of the semiconductor device and a p-type nitride semiconductor layer provided on a second main surface of the active layer; The semiconductor layer is provided in contact with the first main surface of the active layer, and includes an n-type nitride semiconductor containing indium and gallium or an n-type nitride semiconductor.
A first n-type cladding layer made of n-type GaN;
It is provided at a position farther from the active layer than the mold cladding layer,
A second n-type cladding layer having a larger band gap than the first n-type cladding layer, and the p-type nitride semiconductor further includes a p-type contact layer made of p-type GaN. Is provided.

In the third aspect, the first n-type cladding layer preferably has a thickness of 10 Å to 1.0 μm.

According to a fourth aspect of the present invention, an active layer having a quantum well structure having a first main surface and a second main surface and including a nitride semiconductor containing indium and gallium,
A semiconductor laminated structure having an n-type nitride semiconductor layer provided on a first main surface of the active layer and a p-type nitride semiconductor layer provided on a second main surface; The semiconductor layer is provided in contact with the first main surface of the active layer, and includes an n-type nitride semiconductor containing indium and gallium or an n-type nitride semiconductor.
-Type GaN or a first n-type cladding layer, and an n-type nitride semiconductor provided at a position further away from the active layer than the first n-type cladding layer and containing n-type GaN or aluminum and gallium A second n-type cladding layer comprising: a first n-type cladding layer, wherein the p-type nitride semiconductor layer is provided in contact with a second main surface of the active layer, and comprises a p-type nitride semiconductor containing aluminum and gallium. A first p-type cladding layer, wherein the first p-type cladding layer has a thickness of not less than 10 Å and not more than 1.0 μm.

According to a fifth aspect of the present invention, the first
An active layer having a quantum well structure having a second main surface and made of a nitride semiconductor containing indium and gallium; an n-type nitride semiconductor layer provided on a first main surface of the active layer; A semiconductor laminated structure having a p-type nitride semiconductor layer provided on a second main surface of the active layer, wherein the n-type nitride semiconductor layer is provided in contact with the first main surface of the active layer A first n-type cladding layer made of n-type nitride semiconductor or n-type GaN containing indium and gallium, wherein the p-type nitride semiconductor layer is in contact with a second main surface of the active layer. A first p-type layer formed of a p-type nitride semiconductor containing aluminum and gallium, and a first p-type GaN layer provided at a position further away from the active layer than the first p-type layer. Provided is a nitride semiconductor light emitting device comprising two p-type layers It is.

In the present invention, the active layer forms a single quantum well structure composed of a well layer having a thickness of 100 Å or less, or a well layer composed of a nitride semiconductor containing indium and gallium and a nitride semiconductor. A multiple quantum well structure can be formed by stacking the barrier layer and the barrier layer.

In the present invention, the active layer is preferably non-doped.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. Note that, throughout the drawings, similar parts are often denoted by the same reference numerals.

FIG. 1 is a schematic sectional view showing the structure of one embodiment of the nitride semiconductor light emitting device according to the present invention.

The nitride semiconductor light emitting device 10 shown in FIG.
The active layer 15 and the first layer sandwiching the active layer 15 on both sides
Has a semiconductor laminated structure including the n-type cladding layer 14 and the p-type cladding layer 16. This semiconductor laminated structure is provided on a substrate 11 via a buffer layer 12 and an n-type contact layer 13.

The active layer 15 includes a nitride semiconductor containing indium and gallium. A nitride semiconductor containing indium and gallium can be represented by In _m Al _n Ga _1-mn N (where 0 <m <1, 0 ≦ n <1, and m + n = 1). Most preferably, the active layer 15 is of the formula In _m G
a _1-m N (here, 0 <m <1) is included. By changing the ratio of indium, that is, the value of m in each formula, the band gap can be changed so as to obtain light emission in the region from ultraviolet to red. In the following description, the formula In _m Ga _1-m N
(Here, a nitride semiconductor represented by 0 <m <1) or an equivalent formula may be simply referred to as InGaN.

The active layer 15 has a quantum well structure. By making the active layer 15 a quantum well structure, LE
A high-output light-emitting element can be realized by a strained quantum well effect, an exciton light-emitting effect, or the like, whether it is a D element or an LD element.

In the present invention, the term “quantum well structure” refers to a structure in which light emission between quantum levels of a nitride semiconductor (InGaN) constituting an active layer is generated, and both a single quantum well structure and a multiple quantum well structure are used. It is a concept that includes.

The single quantum well structure refers to a structure in which the well layer is composed of a single layer of a nitride semiconductor having a single composition. That is,
An active layer having a single quantum well structure is composed of only a single well layer.
Two cladding layers sandwiching GaN) on both sides constitute a barrier layer.

The multiple quantum well structure refers to a multilayer structure in which well layers and barrier layers are sequentially stacked. The minimum stacked structure of the multiple quantum well structure is a three-layer structure including one barrier layer and (two) well layers provided on both sides of the barrier layer, or a single well layer and provided on both sides thereof (2 And three barrier layers. In the multiple quantum well structure, the two outermost layers on both sides are respectively constituted by a well layer or a barrier layer. In the case of a multiple quantum well structure in which the two outermost layers of the active layer are each constituted by a well layer, two cladding layers sandwiching the active layer on both sides constitute a barrier layer. In the active layer having the multiple quantum well structure, both the well layer and the barrier layer can be formed of a nitride semiconductor containing indium and gallium (preferably, InGaN) (although the compositions of the two are different).
The well layer may be formed of a nitride semiconductor containing indium and gallium (preferably, InGaN), and the barrier layer may be formed of another nitride semiconductor, for example, InN or GaN. That is, the active layer having the multiple quantum well structure also includes a nitride semiconductor containing indium and gallium.

In the case of a single quantum well structure, the active layer 15 is formed with a well layer having a thickness of 100 angstroms or less, and in the case of a multiple quantum well structure, each well layer is formed with a thickness of 100 angstroms or less and each barrier layer is formed. Preferably, the layer is formed to a thickness of no more than 150 angstroms. In any case, the well layer preferably has a thickness of 70 angstroms or less, and most preferably has a thickness of 50 angstroms or less. More preferably, the barrier layer in the active layer is formed to a thickness of 100 Å or less. It is particularly preferred that the active layer of the multiple quantum well structure has a thickness of 200 Angstroms or more, and can typically have a thickness of up to 0.5 μm.

In either the single quantum well structure or the multiple quantum well structure active layer 15, the active layer may be either n-type or p-type. Inter luminescence, exciton luminescence, or quantum well level luminescence is particularly preferred.

When the active layer 15 is doped with a donor impurity and / or an acceptor impurity, if the crystallinity of the active layer doped with the impurity is substantially the same as that of the non-doped active layer, the donor impurity is doped. The active layer thus doped can have a higher inter-band emission intensity than the non-doped active layer, while the active layer doped with the acceptor impurity has an energy lower by about 0.5 eV than the peak wavelength of the original inter-band emission. Although the shifted emission peak wavelength is shown, the half width tends to be wide. When doping both the acceptor impurity and the donor impurity,
The emission intensity of the active layer doped only with the acceptor impurity can be further increased. In particular, when an active layer doped with an acceptor impurity is to be obtained, the conductivity type of the active layer is preferably made n-type by doping also a donor impurity such as Si.

However, in the present invention, since it is ideal that the active layer emits light strongly by inter-band light emission, it is most preferable that the active layer 15 is not doped with impurities. Further, a light-emitting element having a non-doped active layer can have a lower Vf (forward voltage) than a light-emitting element having an active layer doped with impurities.

The first n-type cladding layer 14 provided in contact with the first main surface of the active layer 15 is formed of an n-type nitride semiconductor containing indium and gallium. Since the nitride semiconductor containing In and Ga has a relatively soft crystal, it acts as a so-called buffer layer, and as described below, other nitrides that can be formed on the active layer 15 and itself or on it. Cracks are less likely to occur in the semiconductor layer, and the crystallinity thereof is not deteriorated, so that the light emitting output of the light emitting element is improved. First n-type cladding layer 14
Is preferably formed by n-type _{In j Ga 1-j N (} 0 <j <1). In this In _j Ga ₁ -jN, the value of j is preferably in the range of 0 <j ≦ 0.5. In general, InGaN tends to gradually deteriorate in crystallinity as the ratio of In increases, and in order for the light emitting device to emit light with a high light output practically as an n-type cladding layer, the j value is 0. It is preferably not more than 0.5. The j value is more preferably in the range 0 <j ≦ 0.3, most preferably 0 <j ≦ 0.2.

The carrier concentration of the first n-type cladding layer 14 is desirably in the range of 1 × 10 ¹⁸ / cm ³ to 1 × 10 ²⁰ / cm ³ . If the carrier concentration in the n-type cladding layer 14 is less than 1 × 10 ¹⁸ / cm ^{3, the} efficiency of electron injection into the active layer 15 tends to decrease, and the light emission output tends to decrease. This is because if the carrier concentration is higher than 1 × 10 ²⁰ / cm ³ , the crystallinity of the first n-type cladding layer becomes poor, and the light emission output tends to decrease.

Although the thickness of the first n-type cladding layer 14 is not particularly limited, the total thickness of the active layer 15 and the first n-type cladding layer 14 is 300 Å or more. Is desirable. The total thickness of the nitride semiconductor layer containing In and Ga (active layer + first n-type cladding layer) is 30
If the thickness is smaller than 0 Å, the lattice constant irregularity and the coefficient of thermal expansion of the active layer 15 and the first n-type cladding layer 14, and further another nitride semiconductor layer provided in contact with the first n-type cladding layer, are reduced. This is because cracks are likely to occur due to strain stress that may be present at the interface due to the difference between them. As described above, the nitride semiconductor containing In and Ga is useful for relieving this stress because the crystal is relatively soft, but the total thickness is formed to be 300 Å or more. By doing so, the stress is further alleviated. This total thickness is preferably 1 μm or less.

The p-type cladding layer 16 formed in contact with the second main surface of the active layer 15 is formed of a p-type nitride semiconductor. Such a nitride semiconductor has the formula In _s Al _t G
a _{1- st} N (where 0 ≦ s, 0 ≦ t, s + t ≦ 1).

The substrate 11 is made of sapphire (C-plane, R-plane, A-plane).
Surface, SiC (including 6H-SiC and 4H-SiC), Si, ZnO, GaAs, spinel (MgAl
2 O 4, especially its (111) plane, can be formed of GaN, an oxide single crystal having a lattice constant close to that of a nitride semiconductor, or the like. Generally, sapphire, spinel, GaN or SiC is used. .

The buffer layer 1 formed on the substrate 11
2 is usually formed to alleviate lattice mismatch between the substrate 11 and the nitride semiconductor layer formed thereon, and is formed of, for example, GaN, AlN, GaAlN or the like to a thickness of several hundred angstroms. Is done. Note that the substrate 11 has a lattice constant close to that of the nitride semiconductor formed thereon.
This buffer layer 12 may not be formed when it is formed of a material such as C or ZnO, or when the substrate 11 is lattice-matched with a nitride semiconductor formed thereon.

On the buffer layer 12, an n-type contact layer 13 is formed in contact with the first n-type clad layer 14. This n-type contact layer 13 is made of GaN, AlGa
It is preferable to use N or the like.

After each of the predetermined semiconductor layers is formed on the substrate 11, a negative electrode 18 is formed on the surface of the n-type contact layer exposed by etching.

When the n-type contact layer 13 is formed of GaN, a more preferable ohmic contact with the negative electrode 18 is achieved, and the forward voltage (Vf) of the light emitting device is further reduced. In addition, since GaN is superior in crystallinity to other ternary mixed crystal and quaternary mixed crystal nitride semiconductors, the nitride semiconductor layer such as the first n-type cladding layer 14 grown thereon is grown. Since the crystallinity of the light-emitting element can be improved, the light-emitting output of the light-emitting element can be improved.

The carrier concentration of the n-type contact layer 13 is set to 5 × 10 ¹⁷ / cm ³ from the viewpoint of achieving a preferable ohmic contact with the negative electrode 18 and consequently lowering Vf and preventing a reduction in light emission output. ~ 5 × 10 ¹⁹ / c
It is desirably within the range of m ³ .

The negative electrode 18 is made of a metal material containing titanium (Ti) and gold (Au), for example, a laminated structure or alloy thereof, or Ti, from the viewpoint of achieving a preferable ohmic contact with the n-type contact layer 13. Most preferably, it is formed of a metal material containing aluminum (Al), for example, a laminated structure or an alloy thereof. In this case, it is particularly preferable that the negative electrode 18 be formed as a two-layer structure of a titanium layer provided directly in contact with the n-type GaN contact layer 13 and an aluminum layer formed thereon.

A p-type contact layer 17 is formed on the p-type cladding layer 16, and a positive electrode 19 is formed thereon. The p-type contact layer 17 is made of GaN, AlGa
It is preferable to use N or the like. Particularly, when the p-type contact layer 17 is formed of GaN, a more preferable ohmic contact with the positive electrode 19 is achieved, and the V
f can be reduced.

From the viewpoints of achieving a preferable ohmic contact with the positive electrode 19 and consequently lowering Vf and preventing a reduction in light emission output, the carrier concentration of the p-type contact layer 17 is 1 × 10 ¹⁷ / cm ³ -1. It is desirable to be within the range of × 10 ¹⁹ / cm ³ .

The positive electrode 19 is formed of a metal material containing nickel (Ni) and gold (Au), for example, a laminated structure or an alloy thereof, from the viewpoint of achieving a preferable ohmic contact with the p-type contact layer 17. Is most preferred. In this case, it is particularly preferable that the positive electrode 19 be formed as a two-layer structure of a nickel layer provided directly in contact with the p-type GaN contact layer 17 and a gold layer formed thereon.

FIG. 2 shows another embodiment of the nitride semiconductor light emitting device according to the present invention.

The light emitting device 20 shown in FIG. 2 has the same structure as that of FIG. 1 except that a second n-type cladding layer 21 is provided between the first n-type cladding layer 14 and the n-type contact layer 13. It has the same structure as the semiconductor device.

In the light emitting device 20, the second n-type cladding layer 21 provided in addition to the light emitting device structure shown in FIG. 1 is formed of an n-type nitride semiconductor containing aluminum and gallium. By providing such a second n-type cladding layer 21, the band gap difference between the second n-type cladding layer 21 and the first n-type cladding layer 14 can be increased, and the luminous efficiency of the light emitting element can be improved.

The second n-type cladding layer 21 is preferably formed of n-type Al _a Ga ₁ -aN (here, 0 <a <1). In this case, the value of a is 0 <a ≦
It is preferably in the range of 0.6. When AlGaN has a relatively hard crystal and is larger than 0.6, cracks are relatively likely to occur in the first n-type cladding layer 14 irrespective of the existence of the first n-type cladding layer 14, and the light emission output tends to decrease. Because there is. Most preferably, the value a is in the range of 0 <a ≦ 0.4. In this specification,
A nitride semiconductor represented by Al _a Ga _1-a N or an equivalent formula may be simply referred to as AlGaN.

The carrier of the second n-type cladding layer 21 is
The concentration is 5 × 10¹⁷/ Cm^Three~ 1 × 10¹⁹/ Cm^Threeof
Desirably within the range. The carrier concentration is 5 ×
10 ¹⁷/ Cm^ThreeLower, the resistivity of AlGaN is high.
, The Vf of the light emitting element increases, and the luminous efficiency decreases.
On the other hand, while the carrier concentration is 1 × 10
¹⁹/ Cm^ThreeIf it is higher than this, the crystallinity of AlGaN deteriorates
This is because the luminous efficiency decreases. Second n-type cladding layer
21 is usually 50 Å to 0.5 μm thick
It can be formed with this.

The substrate 11, the buffer layer 12, the n-type contact layer 13, the n-type cladding layer 14, the active layer 15, the p-type cladding layer 16, the p-type contact layer 17, the negative electrode 18 and the positive electrode 19 As described.

FIG. 3 is a schematic sectional view showing the structure of one embodiment of the nitride semiconductor light emitting device according to the present invention.

The nitride semiconductor light emitting device 30 shown in FIG.
It has an active layer 15, and a semiconductor laminated structure including an n-type clad layer 34 and a first p-type clad layer 36 sandwiching the active layer 15 on both sides. This semiconductor laminated structure is provided on a substrate 11 via a buffer layer 12 and an n-type contact layer 13, similarly to the structure shown in FIG.

The first p-type cladding layer 36 provided in contact with the second main surface of the active layer 15 is formed of a p-type nitride semiconductor containing indium and gallium. Since the nitride semiconductor containing In and Ga has a relatively soft crystal, it acts as a so-called buffer layer, and as described below, other nitride semiconductors which can be formed on the active layer 15 and itself or on it. Cracks are less likely to occur in the layers, so that their crystallinity is not deteriorated, and thus the light emitting output of the light emitting element is improved. The first p-type cladding layer 36
It is desirable to form with p-type In _k Ga _{1 -kN} (0 <k <1). In this In _k Ga _1-k N, the value of k is
It is preferable to be within the range of 0 <k ≦ 0.5. In general, the crystallinity of InGaN tends to gradually deteriorate as the ratio of In increases, and in order for the light emitting device to emit light having a high light output practically as a p-type cladding layer, the k value is 0. It is preferably not more than 0.5. The k value is more preferably in the range 0 <k ≦ 0.3, most preferably 0 <k ≦ 0.2.

The carrier concentration of the first p-type cladding layer 36 is desirably in the range of 1 × 10 ¹⁷ / cm ³ to 1 × 10 ¹⁹ / cm ³ . First p-type cladding layer 3
6 has a carrier concentration of less than 1 × 10 ¹⁷ / cm ^{3, the} efficiency of electron injection into the active layer 15 decreases, and the light emission output tends to decrease. On the other hand, the carrier concentration in the p-type cladding layer 36 decreases. If it is larger than × 10 ¹⁹ / cm ^3, the crystallinity of the first p-type clad layer will be deteriorated, and the light emission output tends to be reduced. The first p-type cladding layer 36 is preferably obtained by the method described for the p-type cladding layer 16 in the structure shown in FIG.

The thickness of the first p-type cladding layer 36 is not particularly limited, but the total thickness of the active layer 15 and the first p-type cladding layer 36 is 300 Å or more. Is desirable. The total thickness of the nitride semiconductor layer containing In and Ga (active layer + first p-type cladding layer) is 30
If the thickness is smaller than 0 Å, the lattice constant irregularity and the coefficient of thermal expansion of the active layer 15 and the first p-type cladding layer 36, and further another nitride semiconductor layer provided in contact with the first p-type cladding layer will be reduced. This is because cracks are likely to occur due to strain stress that may be present at the interface due to the difference between them. As described above, the nitride semiconductor containing In and Ga is useful for relieving this stress because the crystal is relatively soft, but the total thickness is formed to be 300 Å or more. By doing so, the stress is further alleviated. This total thickness is preferably 1 μm or less.

The n-type cladding layer 34 formed in contact with the first main surface of the active layer 15 is formed of an n-type nitride semiconductor. Such a nitride semiconductor has the formula In _u Al _v G
a _{1 -uvN} (where 0 ≦ u, 0 ≦ v, u + v ≦ 1).

The substrate 11, buffer layer 12, n-type contact layer 13, active layer 15, p-type contact layer 17, negative electrode 18 and positive electrode 19 are as described with reference to FIG.

FIG. 4 shows another embodiment of the nitride semiconductor light emitting device according to the present invention.

The light emitting device 40 shown in FIG. 4 has the same structure as that of FIG. 3 except that a second p-type cladding layer 41 is provided between the first p-type cladding layer 36 and the p-type contact layer 17. It has the same structure as the semiconductor device.

In the light emitting device 40, the second p-type cladding layer 41 provided in addition to the light emitting device structure shown in FIG. 3 is formed of a p-type nitride semiconductor containing aluminum and gallium. By providing such a second p-type cladding layer 41, the band gap difference between the second p-type cladding layer 41 and the first p-type cladding layer 36 can be increased, and the luminous efficiency of the light emitting element can be improved.

The second p-type cladding layer 41 is preferably formed of p-type Al _b Ga ₁ -bN (here, 0 <b <1). In this case, the value of b is 0 <b ≦
It is preferably in the range of 0.6. If AlGaN has a relatively hard crystal and is larger than 0.6, cracks are relatively likely to occur in the first p-type cladding layer 36 irrespective of the presence of the first p-type cladding layer 36, and the light emission output tends to decrease. Because there is. Most preferably, the b value is in the range of 0 <b ≦ 0.4.

The carrier of the second p-type cladding layer 41 is
The concentration is 1 × 10¹⁷/ Cm^Three~ 1 × 10¹⁹/ Cm^Threeof
Desirably within the range. The carrier concentration is 1 ×
10 ¹⁷/ Cm^ThreeLower than that, holes are injected into the active layer 15.
Input efficiency and luminous efficiency tend to decrease.
On the other hand, the carrier concentration is 1 × 10¹⁹/ Cm^ThreeHigher than
The crystallinity of AlGaN and AlGaN deteriorate and the luminous efficiency decreases?
It is. The second p-type cladding layer 41 usually has a thickness of 50
Formed with a thickness of 0.5 μm
Can be.

The substrate 11, buffer layer 12, n-type contact layer 13, active layer 15, p-type contact layer 17, negative electrode 18 and positive electrode 19 are as described with reference to FIG. 34 and the first p-type cladding layer 36 are as described with reference to FIG.

FIG. 5 is a schematic sectional view showing the structure of one embodiment of the nitride semiconductor light emitting device according to the present invention.

The nitride semiconductor light emitting device 50 shown in FIG.
A semiconductor multilayer structure including an active layer 15, an n-type semiconductor layer 501 including a first n-type cladding layer 54 sandwiching the active layer 15 on both sides thereof, and a p-type semiconductor layer 502 including a second p-type cladding layer 41. Have. This semiconductor stack structure
Similar to the structure shown in FIG. 1, it is provided on substrate 11 via buffer layer 12 and n-type contact layer 13.
In FIG. 5, the n-type semiconductor layer 501 includes the first n-type cladding layer 54.

The light emitting device 50 can be said to have a semiconductor laminated structure in which the n-type cladding layer structure in the light emitting device 10 shown in FIG. 1 and the p-type cladding layer structure shown in FIG. 4 are combined. Means that the first n-type cladding layer 54 is the first n-type cladding layer 14 shown in FIG.
Can be formed not only by the nitride semiconductor containing indium and gallium, but also by GaN, and it has been found that the same effect is obtained. Further, in this case, it was also found that the first p-type cladding layer 56 may be formed of any p-type nitride semiconductor, similarly to the p-type cladding layer 16 in the light emitting device 10 shown in FIG. . Even with such a semiconductor laminated structure, the light-emitting element exhibits similar excellent characteristics.

More specifically, the first n-type clad layer 54 is formed of an n-type nitride semiconductor containing no aluminum. This first n-type cladding layer 54
It is preferable to form n-type In _w Ga _{1 -w} N (here, 0 ≦ w <1). That is, the first n-type cladding layer 54 can be formed of the n-type nitride semiconductor described for the first n-type cladding layer 14 in the light emitting device 10 shown in FIG. 1 or formed of n-type GaN. can do. For the same reason as described for the first n-type cladding layer 14 in the light emitting device 10 shown in FIG.
Is preferably in the range of 0 ≦ w ≦ 0.5, more preferably 0 <w ≦ 0.3, and most preferably 0 <w ≦ 0.2. For the same reason, the carrier concentration of the first n-type cladding layer 54 is 1 × 10 ¹⁸ /
It is desirable that the density be in the range of cm ³ to 1 × 10 ²⁰ / cm ³ . The thickness of the first n-type cladding layer 54 is not particularly limited, but for the same reason, the active layer 15 and the first n-type cladding layer 54 have a total thickness of 300 Å or more. Preferably, it has a thickness of 1 μm or less.

In the light emitting device 50 shown in FIG. 5, the first p-type cladding layer 56 formed in contact with the second main surface of the active layer may be formed of any p-type nitride semiconductor. Is preferably formed of a p-type nitride semiconductor containing no aluminum. More specifically, the first p-type cladding layer 56 is made of p-type In _x Ga ₁ -xN (where 0 ≦ x
It is desirable to form it in <1). Light emitting device 30 of FIG.
Is preferably in the range of 0 ≦ x ≦ 0.5, more preferably 0 ≦ x ≦ 0, for the same reason as described for the first p-type cladding layer 36 in the above.
3, most preferably in the range of 0 ≦ x ≦ 0.2. The first p-type cladding layer 56 can be formed of GaN in the same manner, and acts similarly as a buffer layer. For the same reason, the carrier concentration of the first p-type cladding layer 56 is also 1 × 10 ¹⁷ / cm ³ to 1 × 10
It is desirable to be within the range of ¹⁹ / cm ³ . Further, the thickness of the first cladding layer 56 is not particularly limited, but for the same reason, it is preferable that the total thickness of the first cladding layer 56 and the active layer 15 is 300 Å or more, and the thickness is 1 μm or less. . The first p-type cladding layer 56
May be omitted, but if this is formed, the first p-type cladding layer acts as a buffer layer, so that cracks are less likely to occur, and it is apparent that the light emitting device exhibits more excellent characteristics. There will be.

The second p-type cladding layer 41 is as described for the second cladding layer 41 in the light emitting device 40 shown in FIG.

The substrate 11, the buffer layer 12, the n-type contact layer 13, the p-type contact layer 17, the negative electrode 18 and the positive electrode 19 are as described for the light emitting device 10 shown in FIG.

FIG. 6 is a schematic sectional view showing the structure of another embodiment of the semiconductor light emitting device according to the present invention. This light emitting device 60 has the same structure as the light emitting device 50 shown in FIG. 5 except that a second n-type cladding layer 21 is additionally formed between the n-type contact layer 13 and the first n-type cladding layer 54. It has a similar structure. The second n-type cladding layer 21 is as described for the second n-type cladding layer 21 in the light emitting device 20 shown in FIG. The first p-type cladding layer 56 is preferably provided rather than omitted, as in the case of the light emitting element 50 shown in FIG.

The nitride semiconductor light emitting devices according to some aspects of the present invention have been described above, but it goes without saying that the structures of these light emitting devices can be applied to both LED devices and LD devices. The LD has, for example, a structure shown in a perspective view in FIG. In FIG. 7, the semiconductor layer 71 on the substrate 11 is a semiconductor layer including the buffer layer 12, the n-type contact layer 13, the first n-type cladding layer, and the second n-type layer when formed. The semiconductor layer 72 formed on the active layer 15 is a semiconductor layer including the first clad layer and the second clad layer and the p-type contact 17 layer when formed as described above. The applied current flows intensively in the region 15 a corresponding to the positive electrode 19 in the active layer 15.

In the case of an LD element, the first n-type cladding layer of any of the light emitting elements 10 to 60 and n
If a second n-type cladding layer is formed between the second n-type cladding layer and the n-type cladding layer,
A second p-type cladding layer is formed between the p-type contact layer 13 and / or the first p-type cladding layer and the p-type contact layer 17 of any of the light emitting elements 10 to 60; In this case, a multilayer film formed by laminating at least two types of nitride semiconductor layers having different compositions from each other is formed as a light reflecting film between the second p-type cladding layer and the n-type contact layer 13. You can also.

FIG. 8 shows an example in which the multilayer light reflecting film is applied to the light emitting device structure shown in FIG. In the nitride semiconductor light emitting device 80 shown in FIG. 8, a first multilayer light reflecting film (n-type) 81 is provided between the n-type contact layer 13 and the second n-type cladding layer 21.
And a second multilayer light reflecting film (p-type) 82 between the second p-type cladding layer 41 and the p-type contact layer 17.

First multilayer film 81 and second multilayer film 82
Are nitride semiconductors having different compositions from each other, that is, nitride semiconductors having different refractive indices. Each of the layers is, for example, λ / 4n (where λ is the wavelength of light emitted from the active layer 15 and n is the refractive index). ) Are alternately laminated with two or more layers with a thickness calculated in (1), and are designed so that light emitted from the active layer 15 can be reflected by these films. When the positive electrode 19 is formed as a stripe electrode having a width of, for example, 10 μm or less as shown in FIG. 7 and laser oscillation is performed, light emitted from the active layer 15 can be confined in the active layer 15 by the multilayer reflective layer. Since laser oscillation can be further facilitated, laser oscillation can be easily performed. Also in the LED mode, leakage of emitted light is suppressed by the multilayer reflective layer,
External quantum efficiency is improved.

Each of the multilayer light reflecting films 81 and 82 is doped with a donor impurity and an acceptor impurity to have a predetermined conductivity type.

In the structure shown in FIG. 8, the first multi-light reflecting layer film 81 is formed by the n-type contact layer 13 and the second n-type contact layer 13.
Although formed between the mold cladding layer 21 and the mold clad layer 21, it can be formed in the n-type contact layer 13 instead. Similarly, the second multilayer light reflection film 82 may be formed in the p-type contact layer 17. Even when the multilayer light reflecting film is formed in the contact layer, the light emitted from the active layer 16 can be similarly confined. Either the first multilayer light reflecting film 81 or the second multilayer light reflecting film 82 may be omitted.

As shown in FIG. 8, when a laser device is manufactured using an insulating material such as sapphire as the substrate 11, the structure of the laser device is a flip-chip type.
That is, both the positive and negative electrodes 19 and 1 are on the same surface side of the substrate 11, more specifically, on the side of the substrate 11 where the nitride semiconductor layer is formed.
8 is formed. In this case, as shown in FIG. 8, the first multilayer light reflecting film 81 formed on the n-type layer side is on the p-layer side, that is, above the horizontal plane of the n-type contact layer 13 on which the negative electrode 18 is formed. It is preferable to form it in a position. When the first multilayer light reflecting film 81 is formed closer to the substrate 11 than the horizontal surface of the n-type contact layer 13, the second n
Since the difference in the refractive index between the mold cladding layer 21 and the n-type contact layer 13 is small, light emitted from the active layer 15 spreads into the n-type contact layer 13 located below the active layer 15. This is because sufficient light confinement may not be achieved. This is a phenomenon unique to a nitride semiconductor laser using an insulating substrate such as sapphire.

[0078] Now, two nitride semiconductor constituting the respective multi-layer optical reflecting film 81 and 82, the nitride semiconductor at least one of which contains indium and gallium (for example an In _q Ga
It is preferably _1-qN (where 0 <q <1) or GaN. Because, when a single layer is laminated to form a multilayer light reflection film, one of the single layers is formed of InGaN or Ga.
By forming with N, the InGaN or GaN
This is because the layer acts like a buffer layer and can prevent the other single layer from cracking. This is because the crystal of the InGaN layer and the GaN layer is AlGa
This is due to being softer than N. On the other hand, for example, the multilayer light reflecting film is made of Al having different Al compositions from each other.
If a GaN layer is used to form a multilayer having a total film thickness of, for example, 0.5 μm or more, cracks occur in the multilayer film, and it becomes difficult to manufacture an element.

Two types of nitrides constituting each multilayer light reflecting film
The best combination of semiconductor layers is one with I
n_cGa_1-cFormed of N or GaN and the other is Al
Nitride semiconductor containing minium and / or gallium
(For example, Al_cGa_1-cN (where 0 ≦ c <1)
Some are formed by: In_qGa_1-qN and Al_cGa
_1-cSince N has a large difference in the refractive index, these materials are often used.
By forming a layered light reflection film, the reflection of light
It becomes possible to design a multilayer light reflection film having a large emissivity. Also,
In_qGa_1-qSince N can act as a buffer layer,
Al_cGa_1-c10 layers or less without cracks in the N layer
Can be stacked on top. Note that InN, GaN, and
And AlN have refractive indices of 2.9, 2.5 and 2.5, respectively.
And 2.15. The refractive index of these mixed crystals is
Assuming to obey the law, calculated as proportional to composition
be able to.

FIG. 9 is a schematic sectional view showing a structure of one embodiment of a nitride semiconductor light emitting device according to the present invention, and shows a structure as an LD device.

The nitride semiconductor light emitting device 90 shown in FIG.
It has an active layer 95 and a semiconductor laminated structure including an n-type nitride semiconductor layer 94 and a p-type nitride semiconductor layer 96 sandwiching the active layer 95 on both sides. This semiconductor stack structure
Through the buffer layer 92 and the n-type contact layer 93,
It is provided on a substrate 91.

Active layer 95 has a quantum well structure (single quantum well structure or multiple quantum well structure) including a nitride semiconductor containing indium and gallium, similarly to active layer 15 in semiconductor light emitting device 10 shown in FIG. The description of the active layer 15 is applied to the active layer 95 as it is.

P-type nitride semiconductor layer 96 is formed on first p-type cladding layer 96a formed directly in contact with the second main surface of active layer 95 and on first p-type cladding layer 96a. And a second p-type cladding layer 96b.

The first p-type cladding layer 96a is formed of a p-type nitride semiconductor containing aluminum and gallium. When the first p-type cladding layer 96a is formed of a nitride semiconductor containing aluminum and gallium, light confinement in the active layer 95, which may be insufficient due to the quantum well structure, becomes more complete, and thus the first p-type cladding layer 95
Has been found to act as a good light guide layer for confining light in the active layer 95.

The first p-type cladding layer 96a is made of p-type Al
_d Ga _1-d N (where, 0 <d <1) is most preferably formed. This is because a p-type AlGaN having a high carrier concentration can be easily obtained, and the band gap difference and the refractive index difference can be made larger with respect to the active layer 95 containing InGaN than with other nitride semiconductors. In addition, p-type AlGaN has a property that it is less likely to be decomposed at the time of growth than other nitride semiconductors. For example, the p-type AlGaN has a lower side when it is grown by metal organic vapor phase epitaxy (MOVPE). Active layer 95 of InGaN
Is suppressed, and as a result, the active layer 95 having excellent crystallinity is provided, thereby improving the output of the light emitting element.

The first p-type cladding layer 96a preferably has a thickness of not less than 10 Å and not more than 1.0 μm. If the thickness is less than 10 Å, the effect of providing the first p-type cladding layer cannot be obtained,
On the other hand, if the thickness is more than 1.0 μm, the first p-type cladding layer itself is liable to crack, which tends to make element fabrication difficult. First p-type cladding layer 96
a more preferably has a thickness of 10 Å to 0.5 μm.

It is generally preferable that the first p-type cladding layer 96a has a thickness within the above range including the case of an LED element. In particular, in the case of an LD element, the thickness is preferably 100 Å or more. For this reason, it is more preferable to have a thickness of 1.0 μm or less. If the thickness is smaller than 100 angstroms, the first p-type clad layer is less likely to function as a light guide layer. In this case, the first p-type cladding layer 96a
Most preferably, it has a thickness of 0 Å to 0.5 μm.

The second p-type cladding layer 96b provided on the first p-type cladding layer 96a has a larger band gap than the first p-type cladding layer 96a, and is a p-type nitride semiconductor containing aluminum and gallium. Is formed. The second p-type cladding layer 9 is made of such a p-type nitride semiconductor.
It has been found that by forming 6b, the second cladding layer effectively functions as a light confinement layer, and an effective LD element or the like can be provided.

The second p-type cladding layer 96b also has the first p-type cladding layer 96b.
As in the case of the mold cladding layer 96a, it is easy to obtain a p-type material having a high carrier concentration.
l _e Ga _1-e N (where, 0 <e <1) is most preferably formed. In addition, the second p-type cladding layer 96b
When formed from p-type AlGaN, the difference in band gap and the difference in refractive index from the first p-type cladding layer can be increased, so that the layer functions more effectively as a light confinement layer. Become. The second p-type cladding layer 96b has a larger band gap than the first p-type cladding layer 96a.
The value of f in _e Ga _1-e N is the value of Al _d constituting the latter.
It takes a value larger than the value of e in Ga ₁ -dN. Even in this case, if possible, the d value and the e value in these equations are preferably more than 0 and up to 0.6, and more preferably more than 0 and up to 0.4.

The thickness of the second p-type cladding layer 96b is not particularly limited, but may be 500 Å to 1 Å.
It preferably has a thickness of about μm. By forming the second p-type cladding layer to such a thickness, the occurrence of cracks in itself is reduced, so that the crystallinity is better and the p-type AlGa of high carrier concentration is obtained.
An N layer is obtained.

Note that each of the first p-type cladding layer 96a and the second p-type cladding layer 96b is 1 × 10 ¹⁷
It can be provided as having a high carrier concentration of １1 × 10 ¹⁹ / cm ³ .

Further, the first p-type cladding layer 96a and the second
A layer made of p-type InGaN or p-type GaN between 10 angstroms and 1
It may be formed to a thickness of up to μm. This layer acts as a light guide layer and a buffer layer.

The n-type cladding layer 94 provided in contact with the first main surface of the active layer 95 can be made of any n-type nitride semiconductor. However, since the n-type cladding layer 94 can be formed as a layer having more excellent crystallinity, it is preferable to form the n-type cladding layer 94 from a binary or ternary mixed crystal nitride semiconductor such as GaN, AlGaN, or InGaN. . In particular, by forming the n-type cladding layer 94 of InGaN or GaN, a better active layer 95 can be provided thereon, and the output of the light emitting device is significantly improved.

In the case of an LD device, the n-type cladding layer 94 is desirably formed to a thickness of 100 Å or more and 1 μm or less.

The substrate 91 is the same as the substrate 11 in the light emitting element 10 shown in FIG. 1, and the above description of the substrate 11 can be applied to the substrate 91 as it is.

The buffer layer 9 formed on the substrate 92
2 also represents the buffer layer 12 in the light emitting element 10 shown in FIG.
The description of the buffer layer 12 can be applied to the buffer layer 12 as it is. In a special case, the buffer layer 92 can be omitted.

The n-type contact layer 93 provided on the buffer layer 92 is also the same as the n-type contact layer 93 in the light emitting device 10 shown in FIG.
This is the same as the n-type contact layer 13.
3 can be applied as it is.

The p-type contact layer 97 provided on the second p-type cladding layer 96b is similar to the p-type contact layer 17 in the light emitting device shown in FIG. The above description can be applied to the p-type contact layer 97 as it is.

The negative electrode 98 formed on the exposed surface of the n-type contact layer 93 is the same as the negative electrode 18 in the light emitting device shown in FIG. Can be applied as is.

The positive electrode 99 connected to the p-type contact layer 97 is the same as the positive electrode 19 in the light emitting device shown in FIG. Can be applied as is.
However, in the LD structure shown in FIG. 9, a current confinement layer 100 having a through hole 100a and formed of an insulating material such as silicon dioxide is provided on the p-type contact layer 97. , Through holes 100 of this current confinement layer 100
It is in contact with the p-type contact layer 97 through a.

The present invention has mainly been described with reference to FIG. 9 for an LD element. However, in the case of an LED element, it is not necessary to provide the current confinement layer 100. Also, LE
In the case of a D element, the second p-type cladding layer 96b can be omitted. Further, in the case of an LED element, n
The preferred thickness of the type cladding layer 94 is 10 Å or more and 1.0 μm or less, more preferably 30 Å to 1.0 μm, or the n-type cladding layer 94 itself can be omitted. When the n-type cladding layer 94 is omitted, the n-type contact layer 93 can function as a cladding layer. In the case of the LED element, in the structure shown in FIG. 9, the n-type cladding layer 94 is omitted, the second p-type cladding layer 96b is omitted, the current confinement layer 100 is also omitted, and the n-type contact layer is replaced by n. Active layer having a structure in which a p-type contact layer 97 is formed of p-type GaN, that is, a quantum well structure including a nitride semiconductor containing indium and gallium, on the first main surface thereof An n-type GaN layer is formed on the second main surface of the active layer, a p-type nitride semiconductor layer containing aluminum and gallium is formed, and a p-type GaN layer is formed on the p-type nitride semiconductor. The one having the structure is the most preferable LED element structure. This corresponds to the nitride semiconductor light emitting device according to the present invention.

FIG. 10 is a schematic sectional view showing the structure of one embodiment of the nitride semiconductor light emitting device according to the present invention, and shows a structure as an LD device, similarly to FIG.

The nitride semiconductor light emitting device 200 shown in FIG.
Are an active layer 95, and an n-type nitride semiconductor layer 294 and a p-type nitride semiconductor layer 2 sandwiching the active layer 95 on both sides.
It has a semiconductor lamination structure of 96. This semiconductor multilayer structure is provided on a substrate 91 via a buffer layer 92 and an n-type contact layer 93.

The n-type nitride semiconductor layer 294 includes the active layer 95
A first n-type cladding layer 294a formed in direct contact with the first main surface of the first and second n-type cladding layers 294a
It includes a second n-type cladding layer 294b formed thereon.

The first n-type cladding layer 294a is formed of an n-type G
It is made of aN or an n-type nitride semiconductor containing indium and gallium. If the first n-type cladding layer 294a is formed of GaN or a nitride semiconductor containing indium and gallium, light confinement in the active layer 95, which may be insufficient due to the quantum well structure, becomes more complete, and thus the The first n-type cladding layer 294a not only functions as a good light guide layer for confining light in the active layer 95 (in the case of an LD element), but also the first n-type cladding layer functions as a buffer layer. It has been found that it is possible to reduce the occurrence of cracks in the active layer 95 formed thereon by acting to increase the light emission output of the light emitting element.

The first n-type cladding layer 294a is made of In _r
Most preferably, Ga _1-r N (where 0 <r <1) is used. In this case, the value of r is preferably up to 0.5, more preferably up to 0.3, and even more preferably up to 0.2 for the same reason as described above. Further, the carrier concentration is preferably 1 × 10 ¹⁸ / cm ³ to 1 × 10 ²⁰ / cm ³ for the same reason as described above.

It is preferable that first n-type cladding layer 294a has a thickness of 10 Å or more. By forming the first n-type cladding layer 294a to a thickness of 10 angstroms or more, the first n-type cladding layer 294a more effectively acts as a buffer layer between the active layer 95 and a second n-type cladding layer 294b described later. . That is, the first n
Or Ga constituting the mold cladding layer 294a
N can more effectively absorb the strain caused by the lattice constant mismatch between the second n-type cladding layer 294b and the active layer 23 and the difference in the coefficient of thermal expansion since the crystal is relatively soft. , More effectively function as a buffer layer. As a result, even if the active layer 95 is sufficiently thin, the presence of the first n-type cladding layer 294a causes the active layer 95 and the second n-type cladding layer 294.
b, and furthermore, cracks are less likely to be formed in the p-type cladding layer 296, and the crystallinity thereof is improved, so that the light emitting output of the light emitting element is further increased.

The first n-type cladding layer 294a is formed by an LED
In the case of an element, it is preferable to have a thickness within the above range, and particularly in the case of an LD element, it is particularly preferable to have a thickness of 100 Å or more. If the thickness is less than 100 angstroms, it is difficult to function as a light guide layer.

Further, the first n-type cladding layer 294a is
In any case, it is preferable to have a thickness of 1.0 μm or less. When the thickness is larger than 1.0 μm, the color of the crystal becomes blackish, and a large number of pits tend to be formed in the crystal.
It may be difficult to obtain an LD element.

The second n-type cladding layer 294b provided in contact with the first n-type cladding layer 294a is formed of any nitride semiconductor if the band gap is larger than the first n-type cladding layer 294a. May be used, for example,
It can be formed of a binary or ternary mixed crystal nitride semiconductor such as GaN or AlGaN. By forming the second n-type cladding layer 294b from such an n-type nitride semiconductor, the second n-type cladding layer 294b effectively functions as a light confinement layer, and provides an effective LD element and the like. I knew I could do it.

The second n-type cladding layer 294b is formed of an n-type A
l_fGa_1-fN (where 0 <f <1)
Is most preferred. n-type AlGaN includes InGaN
Band gap difference and refractive index
The difference can be made larger than other nitride semiconductors.
is there. In this case, the value of f is similar to the above-mentioned reason.
For reasons, it is preferred to take values up to 0.6,
It is more preferred to take values up to 4. That carrier
The concentration is also 5 × 10 for the same reason as described above. ¹⁷/ Cm
^Three~ 1 × 10¹⁹/ Cm^ThreeIt is preferred that Also the
2 n-type cladding layer 294b and n-type contact layer 93
By providing a layer made of n-type InGaN between
The second n-type cladding layer made of AlGaN
Growing with low crystal cracking with crystallinity
be able to.

The thickness of the second n-type cladding layer 294b is not particularly limited, but is not less than 500 angstroms.
It preferably has a thickness of 1.0 μm or less. By forming the second n-type cladding layer 294b to a thickness within this range, the second n-type cladding layer 294b having excellent crack-free crystallinity can be obtained.
The mold cladding layer 294b is obtained.

The p-type semiconductor layer (cladding layer) 296 provided in contact with the second main surface of the active layer 95 can be formed of any p-type nitride semiconductor. However, the p-type cladding layer 296 is preferably formed of p-type AlGaN because it can be formed as a layer having more excellent crystallinity. The p-type AlGaN has a property that it is less likely to be decomposed during growth than other nitride semiconductors. For example, when the p-type AlGaN is grown by metal organic chemical vapor deposition (MOVPE), the lower active layer The decomposition of InGaN 95 is suppressed, and as a result, the active layer 95 having excellent crystallinity is provided, thereby improving the output of the light emitting element. In this case, it is also preferable that the ratio of aluminum and the carrier concentration have the same values as those of the first p-type cladding layer 96a and the second p-type cladding layer 96b in the light-emitting element 90 shown in FIG. .

In the case of an LD element, the p-type cladding layer 296 is desirably formed with a thickness of 100 Å or more and 1 μm or less.

The active layer 95, the substrate 91, the buffer layer 92 formed on the substrate 91, the n-type contact layer 93 provided on the buffer layer 92, the p-type contact layer 97, the negative electrode 98, Electrode 99 and current confinement layer 1
00 is as described for the light emitting element shown in FIG.

The present invention has mainly been described with reference to FIG. 10 for an LD element. However, in the case of an LED element, it is not necessary to provide the current confinement layer 100. Also, L
In the case of an ED element, the second n-type cladding layer 294b can be omitted. In that case, the n-type contact layer 9
3 acts as a second n-type cladding layer.

FIG. 11 is a schematic sectional view showing the structure of one embodiment of the nitride semiconductor light emitting device according to the present invention, and shows the structure as an LD device, similarly to FIGS. 9 and 10.

A nitride semiconductor light emitting device 300 shown in FIG.
Are an active layer 95, and an n-type nitride semiconductor layer 294 and a p-type nitride semiconductor layer 9 sandwiching the active layer 95 on both sides.
6 having a semiconductor laminated structure. This semiconductor multilayer structure is provided on a substrate 91 via a buffer layer 92 and an n-type contact layer 93.

In the light emitting device 300 shown in FIG. 11, the n-type nitride semiconductor layer 294 (the first n-type clad layer 294a and the second n-type For the p-type nitride semiconductor layer, the p-type nitride semiconductor layer 96 (consisting of the first p-type clad layer 96a and the second p-type clad layer 96b) of the light emitting device 90 shown in FIG. ) Is one of the most preferred embodiments of the present invention. Each of the semiconductor layers and other configurations will be described with reference to FIGS. 9 and 10, including the above description of the thickness of the nitride semiconductor layer which can be omitted particularly in the case of the LED element and the nitride semiconductor layer particularly in the case of the LED element. What was explained can be applied as it is, and no other words are required. Therefore, in the light emitting device shown in FIG. 11, the n-type contact layer 93 is made of n-type GaN, and the second n-type cladding layer 2 is made of n-type GaN.
94b is n-type AlGaN, and the first n-type cladding layer 29
4a is n-type InGaN or n-type GaN; the first p-type cladding layer 96a is p-type AlGaN; the second p-type cladding layer 96b is p-type AlGaN;
It is most preferable that each of the active layers 95 is made of p-type GaN and the active layer 95 is non-doped. Note that L shown in FIG.
In the case of the D element structure, needless to say, the first n-type cladding layer 294a is formed of the light guide layer and the second cladding layer 29a.
It is also apparent that 4b functions as a light confinement layer, the first p-type cladding layer 96a functions as a light guide layer, and the second p-type cladding layer 96b functions as a light confinement layer. Further, a layer made of p-type InGaN or p-type GaN may be formed as a buffer layer between the first p-type cladding layer 96a and the second p-type cladding layer 96b, or the n-type contact layer 93 may be formed.
Between the n-type cladding layer 294b and the second n-type cladding layer 294b.
A layer made of aN may be formed as a buffer layer.

According to the present invention, an active layer having a quantum well structure including a nitride semiconductor containing indium and gallium is provided between an n-type nitride semiconductor layer and a p-type nitride semiconductor layer, The p-type nitride semiconductor layer includes a first p-type cladding layer formed in contact with the active layer and made of a p-type nitride semiconductor containing aluminum and gallium, and the first p-type cladding layer has a thickness of 10 Å or more. , Having a thickness of 1.0 μm or less.

This light-emitting element basically corresponds to a special case where the second p-type cladding layer 96b is omitted from the structure of the light-emitting element 90 shown in FIG. In this special case,
Further, any one of the n-type contact layer 93 and the n-type cladding layer 94 may be omitted from the structure of the light emitting element shown in FIG. 9 (when the n-type cladding layer 94 is omitted,
The n-type contact layer 93 functions as an n-type cladding layer), and the p-type contact layer 97 may be omitted.

Further, in this special case, the second p-type cladding layer 96b in the light emitting device 90 shown in FIG.
Can be formed of p-type GaN or a p-type nitride semiconductor containing indium and gallium (preferably, InGaN), which corresponds to the light emitting device 10 shown in FIG. The description of the n-type cladding layer 14 can be applied. Furthermore, in contact with the n-type cladding layer (first n-type semiconductor layer) corresponding to the n-type cladding layer 94 in the light emitting element 90 shown in FIG. 9, that is, the first n-type cladding layer 94 and the n-type contact layer 9
3, a second n-type nitride semiconductor containing aluminum and gallium (preferably AlG
aN) is also preferred. In this case,
The description of the second n-type cladding layer 21 in the light-emitting element 20 shown in FIG. 2 including the n-type GaN layer can be applied.

FIG. 12 is a schematic sectional view showing a structure of one embodiment of the nitride semiconductor light emitting device according to the present invention, and shows one particularly preferable structure as an LD device. FIG.
It can be said that the nitride semiconductor light-emitting device of the present invention substantially corresponds to the preferred embodiment described with reference to FIG. 6 except for the first p-type cladding layer described below.

A nitride semiconductor light emitting device 400 shown in FIG.
Comprises an active layer 405, on which a first main surface
N-type cladding layer 414 and second n-type cladding layer 424
And an n-type semiconductor layer including an n-type contact layer 403. In addition, the second main surface of the active layer 405 has a first p-type cladding layer 416, a second p-type cladding layer 426, a third p-type cladding layer 436, and a p-type contact as an outermost layer. A p-type nitride semiconductor layer including the layer 407 is provided. In the structure shown in FIG. 12, such a stacked structure is provided over the substrate 401 with the buffer layer 402 interposed therebetween.

The active layer 405 contains a nitride semiconductor containing indium and gallium. The active layer 405 has a structure in which the nitride semiconductor containing indium and gallium emits light between quantum levels, in other words, a quantum well structure. Is configured. The light emitting element 1 shown in FIG.
Everything described for the 0 active layer 15 applies as is. In the case of an LD element, the active layer 405 most preferably has a multiple quantum well structure.

The first n-type clad layer 414 provided in contact with the first main surface of the active layer 405 functions as a light guide layer, and is formed of n containing indium and gallium.
It is formed of a type nitride semiconductor or n-type GaN. More specifically, the first n-type cladding layer 54, (here, 0 ≦ y <1) n-type In _y Ga _1-y N formed by. That is, the first n-type cladding layer 414 is the first n-type cladding layer 1 in the light emitting device 10 shown in FIG.
4 can be formed of n-type InGaN or can be formed of n-type GaN. For the same reason as described for the first n-type cladding layer 14 in the light emitting device 10 shown in FIG. 1, the value of y is 0 ≦ y
It is preferably in the range of ≦ 0.5, more preferably in the range of 0 <y ≦ 0.3, and most preferably in the range of 0 <y ≦ 0.2. For the same reason, the carrier concentration of the first n-type cladding layer 414 is 1 × 10 ¹⁸ / cm ³ to 1 × 1.
Desirably, it is in the range of 0 ²⁰ / cm ³ . The first n
The thickness of the mold cladding layer 414 is not particularly limited, either.
For the same reason, the active layer 15 and the first n-type clad layer 4
14 preferably has a total thickness of 300 Å or more, and may have a thickness of 1 μm or less.

The second n-type cladding layer 424 provided on the first n-type cladding layer functions as a light confinement layer, and has a larger band gap than the first n-type cladding layer 414. And an n-type nitride semiconductor containing aluminum and gallium or n-type GaN. By providing such a second n-type cladding layer 424, the band gap difference between the first n-type cladding layer 414 and the first n-type cladding layer 414 can be increased, and the luminous efficiency of the light-emitting element can be improved.

When the second n-type cladding layer 424 is formed of n-type Al _g Ga _{1 -gN} (here, 0 <g <1), the value of g is 0 <g ≦ 0. .6. AlGaN has a relatively hard crystal,
If it is larger than 6, cracks are relatively likely to occur in the first n-type cladding layer 414 irrespective of the existence of the first n-type cladding layer 414, and the light emission output tends to be reduced. g
Most preferably, the value is in the range 0 <g ≦ 0.4.

The carrier concentration of the second n-type cladding layer 424 is 5 × 10 ¹⁷ / cm ³ to 1 × 10 ¹⁹ / cm ³
Is desirably within the range. The carrier concentration is 5
If the density is lower than × 10 ¹⁷ / cm ³ , the resistivity of AlGaN is particularly high, so that the Vf of the light emitting element tends to be high and the luminous efficiency tends to decrease.
This is because if it is higher than × 10 ¹⁹ / cm ³ , the crystallinity of AlGaN is particularly deteriorated, and the luminous efficiency is reduced.

The second n-type cladding layer 424 usually has a thickness of 5
It can be formed with a thickness of 0 Å to 0.5 μm.

It is formed as the outermost layer of the n-type semiconductor layer (the layer located farthest from the active layer).
(Formed in contact with the second n-type cladding layer 424)
The n-type contact layer 403 is formed of n-type GaN. N-type contact layer 13 in light emitting device 10 of FIG.
Is preferably formed of n-type GaN for the same reason that n-type GaN is preferably formed of n-type GaN.
Is formed. Other carrier concentrations, for example, are preferably the concentrations described as preferable in the case of the n-type contact layer 13 in the light emitting element 10 shown in FIG.

The first p-type clad layer 416 provided in contact with the second main surface of the active layer 405 functions as a cap layer, and serves as the first p-type clad layer in the other embodiments described above. As in the case of the p-type cladding layer, the active layer is prevented from being decomposed to improve the light emitting output of the light emitting device. This first p-type cladding layer 416 is formed of a p-type nitride semiconductor containing aluminum and gallium.
It has been found that providing such a first p-type cladding layer 416 can provide an even more excellent LD element.

This first p-type cladding layer 416 is preferably made of p-type Al _h Ga ₁ -hN (where 0 <h <1).
Is formed. In this case, the value of h is 0 <h ≦
It is preferably in the range of 0.6. This is because the crystal of AlGaN is relatively hard, cracks are relatively easily generated in the layer, and the light emission output tends to decrease. Most preferably, the h value is in the range 0 <h ≦ 0.4.

The carrier concentration of the first p-type cladding layer 416 is 1 × 10 ¹⁷ / cm ³ to 1 × 10 ¹⁹ / cm ^3.
Is desirably within the range. The carrier concentration is 1
If it is lower than × 10 ¹⁷ / cm ^{3, the} efficiency of injecting holes into the active layer 405 tends to decrease, and the luminous efficiency tends to decrease.
On the other hand, if the carrier concentration is higher than 1 × 10 ¹⁹ / cm ³ , the crystallinity of AlGaN deteriorates and the luminous efficiency decreases.

The first p-type cladding layer 416 usually has a thickness of 5
It can be formed with a thickness of 0 Å to 0.5 μm.

Provided on the first p-type cladding layer 416
The second p-type cladding layer 426 is used as an optical guide layer.
P-type nitride semiconductor containing indium and gallium
It is made of a conductor or p-type GaN. More specifically
Means that the first p-type cladding layer 416_zGa
_1-zN (where 0 ≦ z <1) is desirable.
No. First p-type cladding layer in light emitting device 30 of FIG.
For similar reasons as described with respect to 36, the z-value is
It is preferably in the range of 0 ≦ z ≦ 0.5, and furthermore
Preferably in the range of 0 ≦ z ≦ 0.3, most preferably 0
≦ z ≦ 0.2. This first p-type cladding
The layer 416 can also be formed of GaN in a similar manner.
Acts similarly as a key layer. In addition, the first p-type
For the same reason, the carrier concentration of the
10¹⁷/ Cm^Three~ 1 × 10¹⁹/ Cm ^ThreeWithin the range of
Is desirable. Further, the thickness of the first cladding layer 416
There is no particular limitation on the active layer 405 and the active layer 405 for the same reason.
Has a thickness of 300 Å or more in total
Preferably, it may have a thickness of 1 μm or less.

The third p-type cladding layer 436 provided on the second p-type cladding layer 426 functions as a light confinement layer, has a larger band gap than the second p-type cladding layer 426, and It is formed of a p-type nitride semiconductor containing aluminum and gallium. Third such
By providing the p-type cladding layer 436, the band gap difference between the second p-type cladding layer 426 and the second p-type cladding layer 426 can be increased, and the luminous efficiency of the light-emitting element can be improved.

This third p-type cladding layer 436 is preferably made of p-type Al _i Ga ₁ -iN (where 0 <i <1).
Is formed. In this case, the value of i is 0 <i ≦
It is preferably in the range of 0.6. When AlGaN has a relatively hard crystal and is larger than 0.6, cracks are relatively easily generated in the second p-type cladding layer 426 irrespective of the presence of the second p-type cladding layer 426, and the light emission output tends to be reduced. Because there is. Most preferably, the b value is in the range of 0 <b ≦ 0.4.

The carrier concentration of the third p-type cladding layer 436 is 1 × 10 ¹⁷ / cm ³ to 1 × 10 ¹⁹ / cm ³
Is desirably within the range. The carrier concentration is 1
If it is lower than × 10 ¹⁷ / cm ^{3, the} efficiency of injecting holes into the active layer 405 tends to decrease, and the luminous efficiency tends to decrease.
On the other hand, if the carrier concentration is higher than 1 × 10 ¹⁹ / cm ³ , the crystallinity of AlGaN deteriorates and the luminous efficiency decreases. The third p-type cladding layer 436 typically has
It can be formed with a thickness of 0 Å to 0.5 μm.

The p-type semiconductor layer is formed as the outermost layer (the layer located farthest from the active layer 405) (FIG. 12).
The p-type contact layer 407 is provided in contact with the third p-type cladding layer 436. The p-type contact layer 407 is formed of p-type GaN. The p-type contact layer 407 is formed of p-type GaN for the same reason that the p-type contact layer 17 in the light emitting device 10 of FIG. 1 is preferably formed of p-type GaN. Others, for example, carrier concentration,
P-type contact layer 17 in light emitting device 10 shown in FIG.
It is likewise preferred that the concentration is described as preferred in the case of

Substrate 401, buffer layer 402, negative electrode 4
08 and the positive electrode 409 are respectively the substrate 11, the buffer layer 12, and the negative electrode 1 in the light emitting device 10 shown in FIG.
8 and the positive electrode 19 are as described. Further, the current confinement layer 440 having the through hole 440a is also the same as the current confinement layer 1 in the light emitting element 90 shown in FIG.
00 is as described.

Further, according to the present invention, the first and second
Active layer having a quantum well structure made of a nitride semiconductor containing indium and gallium, an n-type nitride semiconductor layer provided on a first main surface of the active layer, and the active layer A semiconductor laminated structure having a p-type nitride semiconductor layer provided on the second main surface of the semiconductor device, wherein the p-type nitride semiconductor layer comprises:
A first p-type layer formed in contact with a second main surface of the active layer and made of a p-type nitride semiconductor containing aluminum and gallium; and a p-type layer provided in contact with the first p-type layer. There is provided a nitride semiconductor light emitting device including a second p-type layer made of type GaN. The light emitting device according to this embodiment has a special structure in which the second p-type cladding layer 96b and the n-type cladding layer 94 are omitted from the structure of the light emitting device 90 shown in FIG. 9 and the p-type contact layer 97 is formed of p-type GaN. This is the case. In this case, the n-type contact layer 93 can be most preferably formed of n-type GaN.

FIG. 13 shows that various nitride semiconductor light emitting devices of the present invention were manufactured by changing the thickness of the well layer of the active layer having the quantum well structure, and the light emission output (relative value) and the thickness of the well layer were compared. The result of examining the relationship is shown in a graph. As can be seen from FIG. 13, when the thickness of the well layer of the active layer of the quantum well structure in the nitride semiconductor light emitting device of the present invention is set to 70 Å or less, the light emitting output of the light emitting device is significantly improved. It can also be seen that when the thickness of the well layer is 50 Å or less, the light emitting output of the light emitting element is further improved. Such a tendency has been confirmed not only in the active layer having a single quantum well structure but also in the active layer having a multiple quantum well structure for all the nitride semiconductor light emitting devices of the present invention. It was also confirmed that one of the two clad layers sandwiched was formed of a p-type nitride semiconductor and the other was formed of an n-type nitride semiconductor.

Therefore, according to the present invention, a quantum well having at least one well layer containing a nitride semiconductor containing indium and gallium between an n-type nitride semiconductor layer and a p-type nitride semiconductor layer The active layer has a structure, and the well layer has
There is provided a nitride semiconductor light emitting device having a thickness of 70 angstroms or less.

FIG. 14 shows that various nitride semiconductor light emitting devices of the present invention were manufactured by changing the thickness of the barrier layer while keeping the thickness of the well layer of the active layer of the multiple quantum well structure constant. FIG. 6 is a graph showing the result of examining the relationship between the relative value) and the thickness of the barrier layer. As can be seen from FIG.
It can be seen that when the thickness of the barrier layer of the active layer having the quantum well structure in the nitride semiconductor light emitting device of the present invention is 150 Å or less, the light emitting output of the light emitting device is significantly improved. It can also be seen that when the thickness of the barrier layer is less than 100 angstroms, the light emitting output of the light emitting device is further improved. Such a tendency was confirmed not only for all the nitride semiconductor light emitting devices of the present invention, but also widely, one of the two cladding layers sandwiching the active layer is formed of a p-type nitride semiconductor, and the other is an n-type. It was also confirmed when formed of a nitride semiconductor.

FIG. 15 shows a light emitting device having a structure similar to the structure shown in FIG. 9 and the light emitting output (relative value) when the thickness of the first p-type cladding layer 96a is changed.
6 is a graph showing a relationship with the graph. More specifically, in the structure shown in FIG. 9, an n-type GaN contact layer 93 is formed on a sapphire substrate 91 via a GaN buffer layer 92 to a thickness of 4 μm, and an n-type InGaN cladding layer 94 is formed.
Is formed to a thickness of 500 angstroms, and an InGaN active layer 95 having a single quantum well structure is formed to a thickness of 20 angstroms, and a first p-type AlGaN cladding layer 9 is formed thereon.
6a is formed with a different thickness, a second p-type AlGaN cladding layer 96b is formed thereon with a thickness of 0.1 μm, and a p-type GaN contact layer 97 is formed with a thickness of 1 μm. This is for an LED element in which an electrode 98 is formed and a positive electrode 99 is formed without providing a current confinement layer 100.

As shown in FIG. 15, when the thickness of the first p-type cladding layer 96a is greater than 1 μm, the light emission output tends to sharply decrease. At such a thickness, cracks occur in the first p-type cladding layer 96a, and the crystallinity of the element deteriorates. From FIG. 15, L
In the case of an ED element, the thickness of the first p-type cladding layer 96a is 10 Å (0.001 μm) or more,
It is understood that a thickness of μm or less is preferable. Such a tendency was confirmed for all of the nitride semiconductor light emitting devices according to other embodiments of the present invention in which the first p-type cladding layer is formed of AlGaN. As described above, the preferable thickness of the first p-type cladding layer is 100 Å or more in the case of an LD element.

FIG. 16 shows a light emitting device having a structure similar to that shown in FIG.
5 is a graph showing the relationship between the thickness and the light emission output (relative value) when the thickness of the light emitting device is changed. FIG. 16 shows, more specifically, the structure shown in FIG.
An n-type GaN contact layer 93 having a thickness of 4 μm and a second n-type AlGaN cladding layer 294 b having a thickness of 0.1 μm are formed on the first n-type InGaN cladding layer 92 via a GaN buffer layer 92. A layer 294a is formed with a variable thickness, and an InGaN active layer 95 having a single quantum well structure is formed thereon to a thickness of 20 angstroms to form a p-type AlG layer.
This is for an LED element in which an aN cladding layer 296 is formed to a thickness of 0.1 μm, a negative electrode 98 is formed, and a positive electrode 99 is formed without providing a current confinement layer 100.

As can be seen from FIG. 16, when the thickness of the first n-type cladding layer 294a is greater than 1 μm, the light emission output tends to sharply decrease. This is because the crystallinity of the first n-type cladding layer 294a itself deteriorates, for example, the crystal becomes black or pits are generated. Also the first
Even if the thickness of the n-type cladding layer 294a is smaller than 30 Å, the light emission output tends to decrease. This is the first n-type cladding layer 2 made of InGaN.
94a indicates that the preferred film thickness effectively acting as a buffer layer is 30 Å or more. This tendency is due to the fact that the first n-type cladding layer is formed of InG
All of the nitride semiconductor light emitting devices according to other embodiments of the present invention formed of aN or GaN were confirmed. Note that, as described above, the first n-type cladding layer 294a
When the thickness is less than 0 Å, the active layer 95 and the cladding layers 294b and 296 formed thereon do not act as a buffer layer, and a large number of cracks are generated. I do.

Now, in the present invention, the nitride semiconductor is
All of them show n-type even when grown without doping with donor impurities, but most preferably dope with donor impurities such as Si, Ge, Te, and S during crystal growth of the nitride semiconductor. By adjusting the donor impurity concentration, the carrier concentration of the n-type nitride semiconductor layer can be adjusted.

In the present invention, any of the p-type nitride semiconductor layers may be made of Mg, Z
It is obtained by doping acceptor impurities such as n, Cd, Ca, Be, and C during crystal growth of the nitride semiconductor. By annealing the nitride semiconductor layer grown by doping the acceptor impurity at a temperature of 400 ° C. or higher, a more preferable p-type nitride semiconductor layer can be obtained. By adjusting the concentration of the acceptor impurity, the carrier concentration of the p-type nitride semiconductor layer can be adjusted.

The nitride semiconductor light emitting device of the present invention employs a vapor growth method such as MOVPE (metal organic chemical vapor deposition), MBE (molecular beam vapor deposition), and HDVPE (hydride vapor phase epitaxy). Then, it can be preferably manufactured by forming each nitride semiconductor layer on a substrate. For example, an organic MOVP can be obtained by using a nitride semiconductor source such as an organic indium compound, an organic gallium compound, an organic aluminum compound, or ammonia, and using an impurity source as necessary.
By forming each nitride semiconductor layer on the substrate by the E method, and forming a positive electrode and a negative electrode, the nitride semiconductor light emitting device of the present invention can be manufactured.

As described above, the embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to these embodiments. For example, the current confinement layer 100 in FIG. 9 can be applied to the semiconductor light emitting device of the present invention in the case where the device is an LD device. Further, the description regarding the indium ratio and the carrier concentration for one n-type or p-type InGaN layer applies similarly to the other n-type or p-type InGaN layer.
It will be clear that the description of the aluminum ratio and carrier concentration for the layers applies equally to other n-type or p-type AlGaN layers. In addition,
As is clear from the above description, the main surface means a surface on which another layer is formed in the nitride semiconductor layer (specifically, the active layer).

[0154]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. In the following examples, all nitride semiconductor layers are grown by MOVPE.

Example 1 First, using TMG (trimethylgallium) and NH ₃ as source gases, a buffer layer made of GaN was formed at 500 ° C. on a C-plane of a sapphire substrate set in a reaction vessel.
Grown to angstrom thickness.

Next, the temperature was raised to 1050 ° C., and TMG and
NH_ThreeA silane gas is added to the raw material gas
An n-type contact layer made of doped n-type GaN is
Grown to thickness. The electron carrier of this n-type contact layer
The concentration is 2 × 10¹⁹/ Cm ^ThreeMet.

Subsequently, TMA (trimethylaluminum) was further added to the raw material gas, and
a second n-type clad layer made of i-doped n-type Al _0.3 Ga _0.7 N layer was grown to a thickness of 0.1 [mu] m. This second
The electron carrier concentration of the n-type cladding layer is 1 × 10 ¹⁹ / c
m ³ .

Next, the temperature was lowered to 800 ° C., and TMG, TMI (trimethylindium), NH ₃
Si-doped n-type In _0.01 Ga
_A first n-type cladding layer of _0.99 N was grown to a thickness of 500 Å. The electron carrier concentration of this first n-type cladding layer was 5 × 10 ¹⁸ / cm ³ .

Subsequently, TMG, TMI and NH ₃ were used as source gases at 800 ° C. for non-doped In _0.05 Ga
An active layer having a single quantum well structure was formed by growing _0.95 N to a thickness of 30 Å.

Next, the temperature was raised to 1050 ° C., and TMG, TMA, NH ₃ and Cp ₂ Mg (cyclopentadienyl magnesium) were used as source gases, and Mg-doped p was used.
A second p-type cladding layer of type Al _0.3 Ga _0.7 N was grown to a thickness of 0.1 μm. The hole carrier concentration of this second p-type cladding layer was 1 × 10 ¹⁸ / cm ³ .

Subsequently, TMG, NH ₃ and Cp ₂ Mg were used as source gases, and Mg-doped p-type G
A p-type contact layer made of aN was grown to a thickness of 0.5 μm. The hole carrier concentration of this p-type contact layer was 5 × 10 ¹⁹ / cm ³ .

Thereafter, the temperature was lowered to room temperature, the wafer was taken out of the reaction vessel, and the wafer was annealed at 700 ° C. to further reduce the resistance of each p-type layer. Next, a mask having a predetermined shape was formed on the surface of the uppermost p-type contact layer, and etching was performed until the surface of the n-type contact layer was exposed. A negative electrode made of Ti and Al was formed on the exposed surface of the n-type contact layer, and a positive electrode made of Ni and Au was formed on the surface of the p-type contact layer.

After forming the electrodes, the wafer was separated into chips of 350 μm square, and an LED element having a directional characteristic of a half-value angle of 15 ° was obtained according to a conventional method. This LED element has a Vf (forward voltage) of 3.5 at If (forward current) of 20 mA.
V, blue light emission with a light emission peak wavelength of 415 nm, and a light emission output of 6 mW. The half width of the light emission spectrum was 20 nm, and light emission with very good color purity was exhibited.

Example 2 A second n-type clad layer composed of a Si-doped n-type Al _0.3 Ga _0.7 N layer was grown on a sapphire substrate in the same manner as in Example 1, and then a second n-type clad layer was formed on the sapphire substrate. Example 1
Under the same conditions as described above, the non-doped In _0.05 Ga _0.95 N
An active layer having a single quantum well structure was formed by growing to a thickness of Å.

Next, on the active layer, TM was used as a source gas.
800 ° C. using G, TMI, NH ₃ and Cp ₂ Mg
In, and the first p-type cladding layer made of Mg-doped p-type In _0.01 Ga _0.99 N was grown to a thickness of 500 angstroms. The hole carrier concentration of the first p-type layer after annealing was 2 × 10 ¹⁷ / cm ³ .

A desired LED element was obtained in the same manner as in Example 1 except for the subsequent growth of the second p-type clad layer and the p-type contact layer. This LED element has an If 20 mA
, Vf 3.5 V, emission peak wavelength 410 nm,
The half width of the emission spectrum is 20 nm, and the emission output is 5 nm.
mW.

Example 3 In the same manner as in Example 1, an Si substrate was formed on a sapphire substrate.
N-type In_0.01Ga _0.99N-type first n-type crack
After growing up to the first n-type cladding layer,
In addition, non-doped In_0.05Ga_0.95N 40 Angstro
To form a single quantum well active layer.
Done.

Subsequently, TMG, TMI,
Using NH ₃ and Cp ₂ Mg, a first p-type cladding layer made of Mg-doped p-type In _0.01 Ga _0.99 N was grown at 800 ° C. to a thickness of 500 Å. The hole carrier concentration of the first p-type clad layer after annealing was 2 × 10 ¹⁷ / cm ³ .

Next, in the same manner as in Example 1, the first p-type
Mg-doped p-type Al on cladding layer _0.3Ga_0.7From N
Grow a second p-type cladding layer, and
Growth of p-type contact layer made of Mg-doped p-type GaN
I let it. Then, in the same manner as in Example 1, the desired LED
An element was obtained. This LED element has Vf at If20mA.
3.5V, emission peak wavelength 410nm, emission spectrum
Was 20 nm, and the light emission output was 6 mW.

Example 4 In the same manner as in Example 1, an Si substrate was formed on a sapphire substrate.
N-type Al_0.3Ga _0.7A second n-type cladding comprising an N layer
After growing the second n-type cladding layer,
A first n-type clad made of Si-doped n-type GaN
The layer was grown to a thickness of 500 Å. This
The electron carrier concentration of the first n-type cladding layer is 2 × 10
¹⁹/ Cm^ThreeMet.

[0171] Next, on the first n-type cladding layer 55 in the same manner as in Example 3, a non-doped In _{0. 05} Ga _0.95 N 40
An active layer having a single quantum well structure was formed by growing to a thickness of Å.

[0172] Next, on the active layer, in the same manner as in Example 1, second p-type cladding layer and a p-type consisting of Mg-doped p-type GaN composed of Mg-doped p-type Al _0.3 Ga _{0. 7} N Contact layers were grown sequentially. Thereafter, an LED element was obtained in the same manner as in Example 1. This LED element is If2
At 0 mA, Vf is 3.5 V, the emission peak wavelength is 415 nm, the half width of the emission spectrum is 20 nm, and the emission output is 5 m.
W.

Example 5 Example 1 was conducted except that the active layer was formed of In _0.2 Ga _0.8 N.
In the same manner as in the above, an LED element was produced. This LED element emitted blue light with a Vf of 3.5 V, an emission peak wavelength of 455 nm, and a half-value width of 20 nm at If mA of 20 mA, and an emission output of 5 mW.

Example 6 This example was performed in the same manner as in Example 1 except for the formation of the active layer. That is, in this embodiment, in order to form an active layer, a non-doped In _0.1 Ga _0.9 N thin film (well layer) is grown to a thickness of 20 Å at 800 ° C. using TMG, TMI and NH ₃ as source gases. I let it. Subsequently, an In _0.02 Ga _0.98 N thin film (barrier layer) is
Angstrom thickness was grown. This operation is alternately repeated three times each, and finally In _0.1 Ga _0.9 N
A thin film (barrier layer) was grown to a thickness of 20 Å to form an active layer having a multiple quantum well structure with a total thickness of 140 Å. The LED element thus obtained is
At 20 mA If, the device emitted blue light with a Vf of 3.5 V and a light emission peak wavelength of 420 nm, and the light emission output was 7 mW.

Example 7 DEZ (diethyl zinc) was used as an acceptor impurity source, silane gas was used as a donor impurity, and a single quantum well structure doped with Si and Zn was used as an active layer.
An LED device was manufactured in the same manner as in Example 1 except that the _0.05 Ga _0.95 N layer was formed to a thickness of 50 Å. This LED element has a Vf3.
It exhibited blue light emission of 5 V, an emission peak wavelength of 450 nm, and a half width of 70 nm, and the emission output was 3 mW.

Embodiment 8 In accordance with the method of Embodiment 1, a silicon dopant is formed on the n-type contact layer.
N-type In_0.01Ga _0.99N-type first n-type crack
Layer, non-doped In_0.05Ga_0.95An active layer made of N,
Mg-doped p-type Al_0.3Ga_0.7A second p-type made of N
Cladding layer and p-type composed of Mg-doped p-type GaN
A contact layer was grown. That is, the second n-type
L in the same manner as in Example 1 except that no pad layer was formed.
An ED element was obtained. This LED element is rated for If20mA.
Vf 3.5 V, emission peak wavelength 410 nm, emission
The output was 5 mW.

Example 9 In the same manner as in Example 1, after growing each semiconductor layer up to the n-type contact layer on the sapphire substrate, the temperature was raised to 8 ° C.
The temperature was lowered to 00 ° C, and TMG, TMI, NH ₃
Si-doped n-type In _0.01 Ga
_A thin film of _0.99 N was grown to a thickness of 380 Å. Next, the temperature was raised to 1050 ° C., and a thin film of Si-doped n-type Al _0.2 Ga _0.8 N was grown to a thickness of 390 Å using TMG, TMA, NH ₃ and silane gas as source gases. These operations are repeated 20 times, and the Si-doped n-type In _0.01 Ga
_0.99 N layer and Si-doped Al _0.2 Ga _0.8 N layer alternately
An n-type multilayer film (first multilayer reflection film) laminated by 0 layers was formed.

Next, the second n-type clad layer, the first n-type clad layer,
An active layer, a first p-type cladding layer, and a second p-type cladding layer were sequentially grown.

Next, the temperature was set to 800 ° C.
TMG, TMI, NH_ThreeAnd Cp_TwoUse Mg
The Mg-doped p-type In is formed on the second p-type clad layer._0.01
Ga _0.99N layer grown to 380 Å thickness
After raising the temperature to 1050 ° C, TM
G, TMA, NH_ThreeAnd Cp_TwoUsing Mg gas, Mg
Doped p-type Al_0.2Ga_0.8N layer 390 Å
Grew to the thickness of the bomb. By repeating these operations, M
g-doped p-type In_0.01Ga_0.99N layer and Mg-doped p-type A
l_0.2Ga_0.8P-type with 10 layers alternately stacked with N layers
A multilayer film (second multilayer reflection film) was formed.

Next, a p-type contact layer was grown on the p-type multilayer film in the same manner as in Example 1.

After the nitride semiconductor layer was etched on the thus obtained wafer in the same manner as in Example 1,
A mask of a predetermined shape is formed on the surface of the uppermost p-type contact layer, and a negative electrode is formed on the n-type contact layer with a width of 50 μm and a positive electrode is formed on the p-type contact layer with a width of 10 μm. did. When the n-type multilayer film is formed on the n-type contact layer in this manner, the horizontal plane forming the negative electrode is n-type.
Lower than the mold multilayer film, that is, on the substrate side.

Next, the surface of the sapphire substrate on which the nitride semiconductor layer is not formed is polished to a thickness of 90 μm, and the M surface of the sapphire substrate surface (corresponding to the side surface of a hexagonal column in a hexagonal system). Side). After scribing, the wafer was divided into chips of 700 μm square to produce a stripe type LD element. In this LD element, the nitride semiconductor layer surface orthogonal to the stripe-shaped positive electrode is used as an optical resonance surface. The surface of the LD element is covered with an insulating film (not shown) made of SiO ₂ except for the surface of each electrode. Next, this chip was set on a heat sink, and after wire bonding each electrode, laser oscillation was attempted at room temperature. As a result, the threshold current density was 1.5 kA / cm ^2.
As a result, laser oscillation having an oscillation wavelength of 390 nm was confirmed.

Example 10 First, TMG and NH ₃ were used as source gases, and the C surface of a sapphire substrate set in a reaction vessel was heated at 500 ° C.
A buffer layer of GaN was grown to a thickness of 200 Å.

Next, the temperature was raised to 1050 ° C.
A silane gas was added to the source gases of NH ₃ and NH ₃ to grow an n-type contact layer made of Si-doped n-type GaN to a thickness of 4 μm.

Then, the temperature was lowered to 800 ° C., and TMI was further added to the raw material gas to form a Si-doped n-type In _0.05 G
A first n-type cladding layer consisting of a _0.95 N layer was grown to a thickness of 500 Å.

Subsequently, at 800 ° C., non-doped In _0.2 Ga _0.8 N was grown to a thickness of 20 angstroms on the first n-type cladding layer to form an active layer having a single quantum well structure.

Next, the temperature was raised to 1050 ° C., and TMG, TMA, NH ₃ and Cp ₂ Mg were used as source gases, and a first p-type clad layer made of Mg-doped p-type Al _0.1 Ga _0.9 N was placed at _0.10 ° C. It was grown to a thickness of 1 μm.

Subsequently, at 1050 ° C., Mg-doped p-type A
The second p-type cladding layer made of _0.3 g _0.7 Ga _0.7 N is coated with 0.1 μm.
It was grown to a thickness of 5 μm.

Subsequently, at 1050 ° C., Mg-doped GaN
A p-type contact layer was grown to a thickness of 1.0 μm.

After the completion of the reaction, the temperature was lowered to room temperature, the wafer was taken out of the reaction vessel, and the wafer was annealed at 700 ° C. to further reduce the resistance of the p-type layer. Next, etching was performed until the surface of the n-type contact layer was exposed from the uppermost p-type contact layer. After etching, p
A layer of SiO ₂ is deposited on the surface of the type contact layer, a hole is provided in the layer to form a current confinement layer, and Ni and A are connected to the p-type contact layer via the hole on the current confinement layer.
A positive electrode made of u was formed. A negative electrode made of Ti and Al was formed on the exposed surface of the n-type contact layer.

Next, the surface of the sapphire substrate on which the nitride semiconductor layer was not formed was polished to a thickness of 90 μm, and the M surface of the sapphire substrate was scribed and forcibly cleaved. Obtained. After a dielectric multilayer film was provided on the cleavage plane, the chip was placed on a heat sink and laser oscillation was attempted at room temperature.
At / cm ² , laser oscillation with an oscillation wavelength of 450 nm was confirmed.

Embodiment 11 In the same manner as in Embodiment 10, a GaN buffer layer was formed on a sapphire substrate to a thickness of 200 angstroms and an n-type Ga
N-type contact layers of N were sequentially formed to a thickness of 4 μm.

Next, the Si-doped n-type Al _0.3 Ga _0.7 N
After forming a second n-type clad layer having a thickness of 0.5 μm, a first n-type clad layer 71 made of Si-doped n-type In _0.05 Ga _0.95 N was formed to a thickness of 500 angstroms.

Next, non-doped In _0.2 Ga _0.8 N was _added to 20
An active layer having a single quantum well structure is formed by growing to a thickness of Å, and an Mg-doped p-type Al _0.3 G
a second p-type cladding layer made of a _{0. 7} N to a thickness of 0.5 [mu] m, then forming a p-type contact layer made of Mg-doped p-type GaN to a thickness of 1 [mu] m.

Thereafter, the laser oscillation of the obtained LD element was attempted in the same manner as in Example 10. As a result, laser oscillation with an oscillation wavelength of 450 nm was confirmed at a threshold current density of 2.0 kA / cm ² .

Example 12 In the same manner as in Example 10, a GaN buffer layer was formed on a sapphire substrate to a thickness of 200 angstroms and an n-type Ga
N-type contact layers of N were sequentially formed to a thickness of 4 μm.

Next, the Si-doped n-type Al _0.3 Ga _0.7 N
After forming a second n-type clad layer having a thickness of 0.5 μm, a first n-type clad layer made of Si-doped n-type In _0.05 Ga _0.95 N was formed with a thickness of 0.1 μm.

Then, non-doped In _0.2 Ga _0.8 N is grown to a thickness of 20 Å to form an active layer having a single quantum well structure, and Mg-doped p-type Al is formed thereon.
_0.1 Ga _0.9 the first p-type cladding layer of N 0.1
μm, and further doped with Mg-doped p-type Al _0.3
0.5 μm of the second p-type cladding layer made of Ga _0.7 N
Finally, a p-type contact layer made of Mg-doped p-type GaN was grown to a thickness of 0.5 μm.

Thereafter, laser oscillation of the obtained LD element was attempted in the same manner as in Example 10.
And a lasing wavelength of 450 n at a threshold current density of 1.0 kA / cm ² lower than the threshold current densities of the LD elements of FIGS.
m laser oscillation was confirmed.

Embodiment 13 This embodiment relates to a structure of the first n-type cladding layer and the active layer.
The procedure was performed in the same manner as in Example 12 except for the composition. That is, the first
As an n-type cladding layer of Si-doped n-type In _0.05Ga
_0.95Instead of N, a Si-doped n-type GaN layer
m. Also, to form an active layer
In addition, non-doped In_0.4Ga_0.630 Å for N well layer
Grown to the thickness of a storm, and then undoped In
_0.08Ga_{0. 92}N barrier layer to 50 Å thickness
The operation of growing is repeated, and the well layer / barrier layer / well
A total thickness of 190 layers with a five-layer structure consisting of a door layer / barrier layer / well layer
Growing active layer with multiple quantum well structure
Was.

Laser oscillation of the obtained LD device was attempted in the same manner as in Example 10. As a result, laser oscillation of 500 nm was shown at a threshold current density of 0.9 kA / cm ² .

Example 14 A sapphire substrate was formed in the same manner as in Example 10 except that a p-type contact layer was formed without forming a second p-type clad layer after forming a first p-type clad layer. Then, each semiconductor layer up to the p-type contact layer was grown. About the obtained wafer, as in Example 10, after lowering the resistance of the p-type nitride semiconductor layer by annealing and etching from the p-type contact layer to the n-type contact layer, the wafer is put on the p-type contact layer. A positive electrode made of Ni and Au was directly formed without forming a current confinement layer, and a negative electrode made of Ti and Al was formed on the exposed surface of the n-type contact layer. Thus, a desired LED element was obtained. This L
The ED device emits blue light with a Vf of 3.5 V and an emission wavelength of 450 nm at If 20 mA, and an emission output of 6 mW.
Met. Further, the half width of the emission spectrum was 20 nm and sharp inter-band emission was exhibited.

Example 15 In the same manner as in Example 10, semiconductor layers up to the p-type contact layer were grown on a sapphire substrate. About the obtained wafer, as in Example 10, after lowering the resistance of the p-type nitride semiconductor layer by annealing and etching from the p-type contact layer to the n-type contact layer, the wafer is put on the p-type contact layer. A positive electrode made of Ni and Au was directly formed without forming a current confinement layer, and a negative electrode made of Ti and Al was formed on the exposed surface of the n-type contact layer. Thus, a desired LED element was obtained. This LE
The D element emitted blue light at a Vf of 3.5 V and an emission wavelength of 450 nm at If 20 mA, and had a high light output of 6 mW. The half width of the emission spectrum was 20 nm, indicating sharp interband emission.

Example 16 In the same manner as in Example 10, GaN was formed on a sapphire substrate.
The buffer layer has a thickness of 200 angstroms, and the n-type G
An n-type contact layer made of aN was sequentially formed to a thickness of 4 μm. This n-type contact layer also functions as a first n-type clad layer in the LED element of this embodiment.

Next, on the n-type contact layer, non-doped In _0.2 Ga _0.8 N was grown to a thickness of 30 Å to form an active layer having a single quantum well structure.

Then, Mg-doped p-type Al _0.1 Ga _0.9
A first p-type cladding layer of N is grown to a thickness of 0.05 μm, and a p-type layer of Mg-doped p-type GaN is formed thereon.
The mold contact layer was grown directly to a thickness of 0.5 μm.

Thereafter, in the same manner as in Example 14, the resistance of the p-type nitride semiconductor layer is lowered by annealing, and etching is performed from the p-type contact layer to the n-type contact layer. A positive electrode made of Ni and Au was directly formed, and a negative electrode made of Ti and Al was formed on the exposed surface of the n-type contact layer. Thus, a desired LED element was obtained. This LED element has an If 20 mA
Showed blue light emission with a Vf of 3.5 V and an emission wavelength of 450 nm, and the emission output was as high as 7 mW. The half-value width of the emission spectrum showed a sharp inter-band emission of 20 nm.

Example 17 An LED element was obtained in the same manner as in Example 16, except that In _0.4 Ga _0.6 N was grown to a thickness of 50 Å as an active layer. This LED element is
The device exhibited green light emission with a Vf of 3.5 V and an emission wavelength of 520 nm at If20 mA, an emission output of 4 mW, and a half-value width of an emission spectrum of 40 nm.

Example 18 An LD element was obtained by performing the same operations as in Example 3 except for the formation of the active layer and the first p-type clad layer. That is, in this embodiment, in order to form an active layer, non-doped In _0.15 Ga _0.85 N is grown to a thickness of 25 Å as a well layer on the first n-type cladding layer, and a non-doped barrier layer is formed thereon. The operation of growing In _0.05 Ga _0.95 N to a thickness of 50 angstroms was repeated 13 times, and finally a non-doped In _0.15 Ga _0.85 N was formed as a well layer.
Is grown to a thickness of 25 angstroms and a total thickness of 100
An active layer having a multiple quantum well structure of 0 Å was formed. Further, as the first p-type cladding layer, Al _0.05 G
a _0.95 N was grown to a thickness of 500 Å. The same processing as in Example 9 was performed on the thus obtained wafer to obtain a desired LD element. This LD element has a threshold current density of 1.0 kA / cm ² and 415 nm.
Laser oscillation.

Example 19 An LD element was obtained by performing the same operations as in Example 3 except for the formation of the active layer. That is, in this embodiment, in order to form an active layer, non-doped In _0.15 Ga _0.85 N is grown to a thickness of 25 Å as a well layer on the first n-type cladding layer, and a non-doped barrier layer is formed thereon. In _0.05
The operation of growing Ga _0.95 N to a thickness of 50 angstroms was repeated 26 times, and finally, non-doped In _0.15 Ga _0.85 N was grown to a thickness of 25 angstroms as a well layer to form a multiple quantum well structure having a total thickness of 1975 angstroms. An active layer was formed. The wafer thus obtained is subjected to the same processing as in Example 9 to obtain a desired LD.
An element was obtained. This LD device exhibited laser oscillation of 415 nm at room temperature and a threshold current density of 1.0 kA / cm ² .

Example 20 The blue LED element obtained in Example 16, the green LED element obtained in Example 17, and a conventional GaAs-based material or AlI
Light output 3 mW, 660 nm made of nGaP-based material
Each one of the red LEDs as one dot
When a full-color LED display having 56 × 256 pixels was produced, the white surface luminance was 10,000 cd and the color reproduction area was wider than that of the television.

[0212]

As described in detail above, according to the present invention,
Provided is a nitride semiconductor light emitting device having a high light emission output and a narrow half width of an emission spectrum.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 2 is a schematic sectional view showing the structure of another embodiment of the nitride semiconductor light emitting device according to the present invention.

FIG. 3 is a schematic sectional view showing a structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 4 is a schematic sectional view showing the structure of another embodiment of the nitride semiconductor light emitting device according to the present invention.

FIG. 5 is a schematic sectional view showing a structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 6 is a schematic sectional view showing the structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 7 is a perspective view showing an example of the structure of the nitride semiconductor laser device of the present invention.

FIG. 8 is a schematic sectional view showing another structure of the nitride semiconductor laser device of the present invention.

FIG. 9 is a schematic sectional view showing the structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 10 is a schematic sectional view showing the structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 11 is a schematic sectional view showing the structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 12 is a schematic sectional view showing the structure of one embodiment of a nitride semiconductor light emitting device according to the present invention.

FIG. 13 is a graph showing the relationship between the thickness of the well layer of the active layer and the light emission output of the light emitting device in the nitride semiconductor light emitting device of the present invention.

FIG. 14 is a graph showing the relationship between the thickness of the barrier layer of the active layer and the light output of the light emitting device in the nitride semiconductor light emitting device of the present invention.

FIG. 15 is a graph showing the relationship between the thickness of the p-type AlGaN cladding layer and the light emission output of the light emitting device in the nitride semiconductor light emitting device of the present invention.

FIG. 16 is a graph showing the relationship between the thickness of the n-type InGaN cladding layer and the light emission output of the light emitting device in the nitride semiconductor light emitting device of the present invention.

[Explanation of symbols]

11, 91, 401 ... substrate 13, 93, 403 ... n-type contact layer 14, 21, 34, 54, 501, 94, 294, 29
4a, 294b, 414, 412 ... n-type cladding layer 15, 95, 405 ... active layer 16, 36, 41, 56, 502, 96, 96a, 96
b, 296,416,426,436 ... p-type cladding layer 17,97,407 ... p-type contact layer 18,98,408 ... negative electrode 19,99,409 ... positive electrode

 ──────────────────────────────────────────────────の Continuation of the front page (31) Priority claim number Japanese Patent Application No. 7-118046 (32) Priority date May 17, 1995 (May 17, 1995) (33) Priority claim country Japan (JP) (72) Inventor Iwasa Adult 491 Kaminakacho Oka, Anan-shi, Tokushima Prefecture Inside Nichika Gaku Kogyo Co., Ltd.

Claims (13)

[Claims] 1. An active layer having a quantum well structure having a first main surface and a second main surface and including a nitride semiconductor containing indium and gallium, and on the first main surface of the active layer. A semiconductor stacked structure having an n-type nitride semiconductor layer provided on the second main surface and a p-type nitride semiconductor layer provided on the second main surface, wherein the n-type nitride semiconductor layer 1 and includes a first n-type cladding layer made of an n-type nitride semiconductor not containing aluminum and comprising a p-type nitride semiconductor containing aluminum and gallium. A second p-type cladding layer made of a nitride semiconductor of the above, further comprising an n-type contact layer made of n-type GaN formed at a position further away from the active layer than the first n-type cladding layer. A nitride semiconductor light emitting device, characterized by: 2. An active layer having a quantum well structure having a first main surface and a second main surface and including a nitride semiconductor containing indium and gallium, and on the first main surface of the active layer. A semiconductor stacked structure having an n-type nitride semiconductor layer provided on the second main surface and a p-type nitride semiconductor layer provided on the second main surface, wherein the n-type nitride semiconductor layer 1 and includes a first n-type cladding layer made of an n-type nitride semiconductor not containing aluminum and comprising a p-type nitride semiconductor containing aluminum and gallium. A second p-type cladding layer made of a nitride semiconductor, and a p-type contact layer made of p-type GaN formed at a position farther from the active layer than the second p-type cladding layer. A nitride semiconductor light emitting device, characterized by: 3. The nitride semiconductor light emitting device according to claim 1, wherein the active layer and the first n-type cladding layer have a total thickness of 300 Å or more. 4. The second n-type nitride semiconductor layer is formed at a position farther from the active layer than the first n-type clad layer, and is made of an n-type nitride semiconductor containing aluminum and gallium. The nitride semiconductor light emitting device according to claim 1, further comprising an n-type clad layer. 5. A first p-type cladding layer provided between an active layer and a second p-type cladding layer and made of a p-type nitride semiconductor not containing aluminum. The nitride semiconductor light emitting device according to any one of claims 1 to 4, comprising: 6. The nitride semiconductor according to claim 5, wherein the active layer, the first n-type cladding layer, and the first p-type cladding layer have a total thickness of 300 Å or more. Light emitting element. 7. An active layer having a quantum well structure including first and second main surfaces and including a nitride semiconductor containing indium and gallium, provided on the first main surface of the active layer. a semiconductor laminated structure having an n-type nitride semiconductor layer and a p-type nitride semiconductor layer provided on a second main surface of the active layer, wherein the n-type nitride semiconductor layer is a third layer of the active layer. A first n-type cladding layer which is provided in contact with the main surface of the first and is made of an n-type nitride semiconductor or n-type GaN containing indium and gallium, and which is farther from the active layer than the first n-type cladding layer. And a second n-type cladding layer having a band gap larger than that of the first n-type cladding layer. The p-type nitride semiconductor further comprises a p-type GaN
A nitride semiconductor light emitting device comprising a p-type contact layer comprising: 8. The nitride semiconductor light emitting device according to claim 7, wherein the first n-type cladding layer has a thickness of not less than 10 Å and not more than 1.0 μm. 9. An active layer having a quantum well structure having a first main surface and a second main surface and including a nitride semiconductor containing indium and gallium, and on the first main surface of the active layer. A semiconductor stacked structure having an n-type nitride semiconductor layer provided on the second main surface and a p-type nitride semiconductor layer provided on the second main surface, wherein the n-type nitride semiconductor layer N-type nitride semiconductor, n-type GaN, or
And a second n-type cladding layer provided at a position further away from the active layer than the first n-type cladding layer and made of n-type GaN or an n-type nitride semiconductor containing aluminum and gallium A first p-type cladding layer provided in contact with a second main surface of the active layer and made of a p-type nitride semiconductor containing aluminum and gallium. A first p-type cladding layer having a thickness of not less than 10 Å and not more than 1.0 μm. 10. An active layer having a quantum well structure having a first and a second main surface and made of a nitride semiconductor containing indium and gallium, and n provided on the first main surface of the active layer.
A semiconductor laminated structure having a p-type nitride semiconductor layer provided on a second main surface of the active layer, wherein the n-type nitride semiconductor layer is a first layer of the active layer. And a first n-type clad layer made of n-type nitride semiconductor or n-type GaN containing indium and gallium, and the p-type nitride semiconductor layer is A first p-type layer formed in contact with the second main surface and made of a p-type nitride semiconductor containing aluminum and gallium, and provided at a position further away from the active layer than the first p-type layer P-type GaN
A nitride semiconductor light-emitting device comprising a second p-type layer comprising: 11. The nitride semiconductor light emitting device according to claim 1, wherein the active layer has a single quantum well structure comprising a well layer having a thickness of 100 Å or less. . 12. The multi-quantum well structure in which an active layer is formed by laminating a well layer made of a nitride semiconductor containing indium and gallium and a barrier layer made of a nitride semiconductor. 11. The nitride semiconductor light-emitting device according to any one of items 10 to 10. 13. The nitride semiconductor light emitting device according to claim 1, wherein the active layer is non-doped.