JP2002232000A - Group-iii nitride semiconductor light-emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Group-III nitride semiconductor light-emitting device having high light-emission intensity, by making a hetero-junction light-emitting region and a current diffusion layer disposed on a silicon single crystal substrate from a good-quality Group-III nitride semiconductor crystalline layer with low crystal defect density. SOLUTION: A light-emitting device with high light-emission intensity is constructed by providing a lattice-matched light-emitting region and a current diffusion layer on a Si substrate via a buffer layer containing phosphorus or arsenic, so that a device driving current is diffused over a wide range of the light-emitting region. For this purpose, a preferable combination of materials of an upper clad layer and the current diffusion layer is specified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting portion having a pn junction type double hetero (DH) junction structure of a lattice matching system and a current for promoting diffusion of a device driving current on a Si single crystal substrate via a buffer layer. The present invention relates to a technique for obtaining a group III nitride semiconductor light emitting diode having high emission intensity by forming a diffusion layer.

[0002]

_2. Description of the Related Art Instead of electrically insulating sapphire (α-Al ₂ O ₃ single crystal) (Mat. Res. Soc. Sym)
p. Proc. , Vol. 468 (1977), 481
486), and a technique for forming a light emitting diode (LED) made of a group III nitride semiconductor using silicon (Si) single crystal (silicon) as a substrate is disclosed (Ele).
ctron. Lett. , 33 (23) (1997),
1986-1987). When a substrate is made of a conductive Si single crystal, an electrode can be laid on the back surface of the substrate, and there is an advantage that an LED can be easily configured. In addition, if a Si single crystal is used as a substrate, there is an advantage that it can be easily divided into individual elements (chips) using cleavage (Appl. Phys. L).
ett. , 72 (4) (1998), pp. 415-417).

[0003] Group III nitride semiconductor light emitting devices include II
A light emitting section having a pn junction type double hetero (DH) junction structure made of a group I nitride semiconductor is provided. The light-emitting unit is a functional unit that emits light and includes a light-emitting layer sandwiched between p-type and n-type clad layers. In the prior art, the cladding layer is hexagonal (hexagon).
al) aluminum gallium nitride (Al _a Ga
_1- aN, where 0 ≦ a ≦ 1). Emitting layer for emitting short wavelength visible light in the blue band or green band, hexagonal gallium indium nitride (Ga _b In _1-b
N, where 0 <b <1) (see Japanese Patent Publication No. 55-3834).

[0004] The lattice constant of the a-axis of wurtzite gallium nitride (GaN) is 3.189 angstroms (Å). The a-axis lattice constants of aluminum nitride (AlN) and indium nitride (InN) are 3.111 ° and 3.533 °, respectively. (The lattice constant values are both Iwao Teramoto, “Introduction to Semiconductor Devices.”)
(March 30, 1995, first edition published by Baifukan Co., Ltd., 28
Page). Therefore, Ga _b In _1-b N (generally 0 <b <1) forming the light emitting layer and Al _a Ga _1-a N (0 ≦ a) forming the cladding layer.
≦ 1), the lattice constant is different. That is, the light-emitting portion of the conventional group III nitride semiconductor LED using a Si single crystal as a substrate has a lattice mismatched structure composed of group III nitride semiconductor layers having different lattice constants (see above). Ap
pl. Phys. Lett, 72 (4) (1998)).

Al provided on a cubic crystal substrate such as gallium phosphide (GaP) via a boron phosphide (BP) buffer layer
There has been disclosed a technique for forming a group III nitride semiconductor LED using a light emitting portion formed of a GaN mixed crystal system layer (see Japanese Patent Application Laid-Open No. 2-288388). Further, using an equiaxed cubic Si single crystal as a substrate, In _x Al _Y Ga _{1 -XYN} (0 ≦
A technique for forming an X, 0 ≦ Y, X + Y = 1) LED has also been disclosed (Japanese Patent Application Laid-Open No. 10-321911). S
In a conventional LED using an i-single crystal as a substrate, a light-emitting portion is composed of a pn-junction type hetero-junction structure of a clad layer made of n-type and p-type Al _0.2 Ga _0.8 N and a light-emitting layer made of GaN. There is an example (JP-A-10-242586). Al _0.2 Ga _0.8 N constituting the cladding layer
And GaN have different lattice constants.
The light emitting portion of a conventional LED using a single crystal as a substrate has a lattice mismatching structure.

In a group III nitride semiconductor laser diode (LD), there is also known a structure in which a contact layer made of a group IIIV nitride compound semiconductor is provided above a light emitting portion (Japanese Patent Application Laid-Open No. 10-242567). For example, a contact (cont) made of boron phosphide (BP) is formed on a clad layer made of an AlGaN-based mixed crystal layer.
There is known a technique for forming an LD by providing an act) layer (Japanese Patent Laid-Open No. Hei 10-242569). In addition, Si
Means of providing a p-type gallium nitride (GaN) contact layer on an upper cladding layer made of p-type Al _0.15 Ga _0.85 N provided on a single crystal substrate has been disclosed (JP-A-11-4).
No. 0850). The lattice constants of Al _0.15 Ga _0.85 N and GaN are different. Therefore, it acts as a good conductive layer for forming an electrode having a low contact resistance, and in particular, LE
In the case of D, the contact layer, which also functions as a current spreading layer for diffusing the element driving current over a wide range of the light emitting portion, has a conventional structure which does not have a lattice matching relationship with the cladding layer as described above. It has been usual to be composed of a group V compound semiconductor.

[0007]

As described above, the light emitting portion of the conventional pn junction type DH structure of the group III-V compound semiconductor light emitting device has a lattice mismatched laminated structure. For this reason, the light emitting layer laminated with the lower clad layer as an underlayer has poor crystallinity including a large amount of crystal defects such as misfit dislocations generated due to lattice mismatch, and has a low light emission intensity. There was a problem that hindered the increase. The intensity of light emitted from the light emitting layer increases as the crystallinity of the light emitting layer becomes better. Therefore, in order to obtain a group III nitride semiconductor light emitting device with high emission intensity,
It is necessary to form the light-emitting layer from a crystal layer having a low density of crystal defects caused by lattice mismatch.

When the light emitting layer and the upper cladding layer do not have a lattice matching relationship, the crystallinity of the upper cladding layer is also disturbed. If a large amount of misfit dislocations and the like are contained in the upper cladding layer, there is a problem that the element driving current locally and intensively flows through the light emitting layer via the dislocations. If the crystallinity of the light-emitting layer serving as the underlayer is poor as described above due to the lattice mismatch, the quality of the upper upper cladding layer is even worse. Therefore, the device operating current cannot be distributed over a wide area of the entire surface of the light emitting layer, which hinders expansion of the light emitting area. In order to distribute the device drive current in a planar manner over a wide range of the light emitting layer, it is necessary to stack an upper clad layer having excellent crystallinity on the light emitting layer having excellent crystal quality.

Further, if the upper cladding layer is a poor quality crystal layer containing a large amount of crystal defects caused by lattice mismatch, it is difficult to stack a current diffusion layer having excellent crystallinity thereon. . An element driving current supplied from an electrode provided on the current diffusion layer may locally short-circuit to the upper cladding layer via a crystal defect such as a misfit dislocation existing in the current diffusion layer, and Therefore, there arises a problem that the light emitting area cannot be sufficiently expanded.

In order to obtain a group III nitride semiconductor light emitting device having a high light emission intensity, it is necessary to constitute a light emitting portion from a group III nitride semiconductor layer having excellent crystallinity capable of diffusing an element driving current over a wide range of the light emitting layer. is there. It is also important that the light emitting layer itself is formed of a group III nitride semiconductor layer having excellent crystallinity. In the present invention, by forming the light emitting portion from a group III nitride semiconductor layer having a lattice matching relationship with each other, a high quality group III nitride semiconductor layer having a low crystal defect density generated due to lattice mismatch can be obtained. Means for constituting a light emitting unit is provided. In addition, a current diffusion layer which can be conveniently used as a contact layer provided on the light emitting portion is formed of a group III-V compound semiconductor layer which is lattice-matched with a constituent layer of the light emitting portion, so that crystal defects caused by lattice mismatch can be reduced. High emission intensity Si that is configured to prevent short-circuit flow of the element driving current to the light emitting portion through the light emitting portion and distribute the current to the light emitting portion almost uniformly.
Technical means for obtaining a substrate-based group III nitride semiconductor LED are provided.

[0011]

That is, the present invention provides (1)
Si single crystal substrate and III containing phosphorus (P) or arsenic (As) provided as constituent elements on the substrate surface
A buffer layer made of a group V compound semiconductor, and a p-type and n-type group III nitride semiconductor which lattice-matches a light emitting layer made of an indium group III nitride semiconductor provided on the buffer layer with the light emitting layer. A group III nitride semiconductor LED comprising at least a light emitting part of a pn junction type double hetero junction structure sandwiched between cladding layers and a current diffusion layer made of a III-V compound semiconductor provided on the light emitting part. provide.

In the present invention, in addition to the constitution of the above-mentioned (1), (2) the clad layer has a multi-phase structure composed of a plurality of phases having different indium composition ratios (indium concentrations). Provided is a group III nitride semiconductor LED comprising a group III nitride semiconductor lattice-matched to a group III nitride semiconductor constituting a main phase of a light emitting layer.

In the present invention, the above (1) or (2)
In addition to the constitution of the invention of (1), (3) I forming the cladding layer
A current diffusion layer comprising a group III-V compound semiconductor containing phosphorus (P) or arsenic (As) as a constituent element, which is lattice-matched with a group II nitride semiconductor, wherein the current diffusion layer is composed of II.
Provided is a Group I nitride semiconductor LED.

In particular, according to the present invention, in the structure of the invention described in the above (3), the cladding layer is made of gallium indium nitride (Ga _x In ₁ -xN, where 0.94 ≦ X ≦ 1). In this case, the current diffusion layer is made of boron nitride phosphide (BN _1-X P _X , where 0.97 ≦ X ≦
It is preferable to configure from 1).

[0015] In the present invention, in the configuration of the invention described in (3) clad layers cubic nitride gallium indium consisting mainly _{(Ga X In 1-X N} : 0.4
3 ≦ X ≦ 1). In this case, the current spreading layer is preferably made of boron arsenide (BN _1-x As _x , where 0.77 ≦ X ≦ 1).

According to the present invention, in addition to the constitution of the invention described in the above (3), the cladding layer has a nitrogen composition ratio of 0.97.
Gallium nitride phosphide (G
It consists of aN _{0. 97} P _0.03). Alternatively, the clad layer of nitrogen composition ratio cubic nitride gallium arsenide consisting mainly to _0.98 (GaN 0.98 As _0.02).
In this case, the current spreading layer is preferably made of boron phosphide (BP).

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a first embodiment of the present invention, n
A stacked structure for use in a group III nitride semiconductor LED is formed using a low-resistance or single-crystal Si single crystal as a substrate. A few milliohm-centimeters (m
(Ω · cm) or less, and a Si single crystal having good conductivity can be suitably used as a substrate. For example, a laminated structure for a so-called n-side-up type LED is formed using a low-resistance n-type Si single crystal to which phosphorus (P), arsenic (As), or antimony (Sb) is added as a substrate. I do. For example, if a low-resistance p-type Si single crystal to which boron (B) is added is used as a substrate, a p-side-up type LE
A laminated structure for application D can be configured.

The plane orientation of the Si single crystal substrate is {100},
It can be selected from {110} or {111}. A Si single crystal having a plane orientation inclined from several degrees to several tens degrees from the low Miller index plane can also be used as the substrate. The {111} crystal plane has denser Si atoms than the {100} crystal plane. Therefore, {111}
-Si single crystal, phosphorus (P) or arsenic (As) S
Diffusion and intrusion into the i-single crystal are effectively suppressed, which is convenient for forming a buffer layer made of a III-V compound semiconductor containing phosphorus (P) or arsenic (As). $ 31
Si having high-order Miller index plane such as 1} or {511}
Single-crystal channeling of phosphorus (P) or arsenic (As) (c)
This is effective in suppressing intrusion into the Si single crystal substrate such as in the case of conducting a channeling process. However, the growth orientation of the upper layer is also higher, reflecting the plane orientation of the substrate surface.
There may be inconveniences such as complicated cutting into D.

A buffer (buff) provided on a Si single crystal substrate
er) layer contains phosphorus (P) or arsenic (As) III
-It is made of a Group V compound semiconductor. For example, it is composed of boron phosphide (BP) or boron arsenide (BAs).
In addition, as a material constituting the buffer layer, a gallium phosphide mixed crystal (GaN _0.02 P _0.98 ) or a gallium arsenide mixed crystal (GaN _0.04 ) having the same lattice constant as a Si single crystal (lattice constant: 5.4309 °) _{. 19} As _0.81 ), gallium boron gallium phosphide mixed crystal (B _0.02 Ga _0.98 P) (JP-A-11-2660)
06 No.), and arsenide boron gallium mixed crystal (B _0.25 Ga
_0.75 As) (JP-A-11-260720). Further, a mixed crystal of indium boron phosphide containing indium (In) as a constituent element (B _0.33 In _0.67 P)
And mixed crystals of indium boron arsenide (B _0.40 In _0.60 As)
Can be composed of Further, it can be composed of a cubic indium nitride phosphide mixed crystal (InN _0.49 P _0.51 ) and an indium nitride arsenide mixed crystal (InN _0.58 As _0.42 ). Since these mixed crystals are lattice-matched with the Si single crystal, a high-quality buffer layer with few crystal defects due to lattice mismatch can be formed. Preferably, the conductivity type of the buffer layer matches the substrate conductivity type.

For example, in the case of boron phosphide (BP) or boron arsenide (BAs) having a different lattice constant from the Si single crystal,
When grown at a relatively low temperature, lattice mismatch (mismatch) with the Si single crystal is alleviated, and the I
A buffer layer having an effect of providing a group II nitride semiconductor layer can be configured. For example, a BP low-temperature buffer layer formed at a relatively low temperature of 250 ° C. or more and 500 ° C. or less has a lattice mismatch with an Si single crystal of about 16% (“Journal of the Japan Society for Crystal Growth”, Vol. 24, No. 2). (1997, p. 150), which is effective in providing a high-quality multi-layered structure having a low density of crystal defects such as misfit dislocations. Generally, several nanometers (nm) to several tens of nm are suitable as the layer thickness of the low-temperature buffer. Impurity doping is applied to the thin film low-temperature buffer layer so as to obtain the same conductivity as that of the Si single crystal substrate.
This is effective in reducing f). On the BP cold buffer layer,
750 ° C. to 1200 which is higher than the growth temperature of the low-temperature buffer layer
There is also a technical means in which a BP high-temperature layer grown at ℃ is overlaid to constitute a buffer layer as a whole (US Pat. No. 6,069,021).
No.).

On the buffer layer, a lower clad layer, which is a constituent layer of a light emitting portion of a pn junction type heterojunction, is laminated. The conduction type of the lower cladding is usually matched to the conduction type of the Si single crystal substrate and the buffer layer. When the cladding layer is made of a group III nitride semiconductor lattice-matched to the buffer layer, the light emitting unit can be made of a group III nitride semiconductor having a low crystal defect density and a high crystallinity due to a lattice mismatch. For example, n-type or p-type boron phosphide (lattice constant =
4.531Å) The nitrogen composition ratio is 0.97 on the buffer layer.
(= 97%) cubic gallium nitride phosphide (Ga
N _0.97 P _0.03 ). Also,
From BP layer and the GaN _0.97 P _0.03 provided the GaN _0.97 buffer layer of each layer of the P _0.03 a multilayer structure with layered alternately can be configured a lower cladding layer lattice-matched to the buffer layer. This multilayer structure has a layer thickness (n
m) is matched to the value given by the relational expression λ / (4 · n) between the emission wavelength (λ: nm) and the refractive index (n), the Bragg reflection layer (Iga and Koyama, “Surface emitting laser”) (199
September 25, 0, 1st Edition, 1st Edition, 1st Edition
(See pages 18 to 119). On the boron arsenide (lattice constant = 4.777 °) buffer layer, cubic GaN _0.72 P _0.28 having a nitrogen composition ratio of 0.72 can be laminated as a lower cladding layer.

On the lower cladding layer, a lower cladding layer
Light emission (active) composed of a lattice-matched group III nitride semiconductor
Layer). For example, lattice matching with the BP buffer layer is achieved.
Addition cubic GaN_0.97P_0.03(Lattice constant = 4.538
Indium (I)
n) Gallium indium nitride having a composition ratio of 0.10.
(Ga _0.90In_0.10N) as a light emitting layer. beneath
III-nitride semiconductor in lattice matching with cladding layer
If the light-emitting layer is composed of the body, crystals such as misfit dislocations
An advantage is that a light emitting layer with low defect density and excellent crystallinity is provided.
There is a point. Further, for example, lattice matching with the BAs buffer layer is performed.
Cubic GaN_0.72P_0.28(Lattice constant = 4.777 °)
Contains Ga with an indium composition ratio of 0.43._0.57In
_0.43An N light emitting layer is laminated. Lower cladding layer as above
A barrier layer from the material of the
Each well layer is formed from an optical layer constituent material.
A single quantum well (SQW) or multiple quantum well (M
The QW) structure can be used as a light emitting layer. this
In this case, since the well layer and the barrier layer are lattice-matched to each other,
A light emitting layer having a well layer with excellent crystallinity is provided.
For this reason, an effect is achieved in increasing the light emission intensity.

The light emitting layer can be composed of an undoped layer to which no impurity is intentionally added. Also, p
It can be made of a group III nitride semiconductor doped with n-type and n-type impurities. As in the case of obtaining an n-type or p-type buffer layer or a lower cladding layer, beryllium (Be),
Magnesium (Mg) or zinc (Zn) can be used as the p-type dopant. Examples of the n-type dopant include Group IV elements such as Si and tin (Sn) or Group VI elements such as sulfur (S), selenium (Se), and tellurium (Te). Amphoteric impurities such as carbon (C) can also be used as dopants. For the buffer layer and the lower cladding layer, for example, LE
It is preferable that impurities are added to D so as to exhibit a carrier concentration that does not cause a sudden increase in the forward voltage (Vf). The carrier concentration is approximately 5 × 10
^{A range of 17} cm ⁻³ or more and 5 × 10 ¹⁹ cm ⁻³ or less is suitable.
If a large amount of impurities are doped in order to obtain a high carrier concentration exceeding about 5 × 10 ¹⁹ cm ⁻³ , distortion may occur in the crystal layer constituting the buffer layer or the cladding layer. Therefore, good lattice matching between the buffer layer and the lower clad layer or between the lower clad layers cannot be maintained, which is inconvenient for obtaining a lower clad layer or a light emitting layer having excellent crystallinity.

The carrier concentration of the light emitting layer is approximately 5 ×
A range of 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is suitable. A carrier concentration in this range can be obtained without doping a large amount of impurities. For this reason, a high-quality light emitting layer can be provided without disturbing the lattice matching with the lower cladding layer. In the case of a light emitting layer having a quantum well structure, a high-resistance group III nitride semiconductor thin layer containing oxygen (O) can be used as a barrier layer or the like.

In the second embodiment of the present invention, the light emitting layer is made of an indium nitride semiconductor having a multiphase structure. Indium-containing nitride semiconductors include boron nitride and indium (B
_X In _{1 -X} N, where 0 ≦ X <1; aluminum indium nitride (Al _X In _1-X N, where 0 ≦ X <1); gallium indium nitride (Ga _X In _1-X N, where 0 ≦ X <
1) The general formula B _α Al _β Ga _γ In _δ N (0 ≦ α, β,
Group III nitride semiconductors represented by γ ≦ 1, 0 <δ ≦ 1, α + β + γ + δ = 1) can be exemplified. In addition, nitrogen (N) and a general formula B containing a group V element other than nitrogen (N), such as phosphorus (P) or arsenic (As), as a constituent element
_α Al _β Ga _γ In _δ N _{1 -Z} M _Z (0 ≦ α, β, γ ≦ 1,
Group III nitride semiconductors represented by 0 <δ ≦ 1, α + β + γ + δ = 1, and 0 <Z <1) are also indium nitride semiconductors. These include, for example, cubic indium phosphide nitride _{(InN 1-Z P Z:} 0 <Z <1), cubic gallium phosphide, indium nitride _{(Ga α In β N 1-} Z P Z,
Where 0 ≦ α ≦ 1, 0 <β ≦ 1, α + β = 1, 0 <Z <
1), cubic indium arsenide nitride (InN ₁ -Z As _Z :
0 <Z <1) or cubic gallium arsenide indium _{nitride, (Ga α In β N 1} -Z As Z, where 0 ≦ α ≦ 1,0
<Β ≦ 1, α + β = 1, 0 <Z <1), etc. The composition ratio of the mixed crystal is set so that the lower clad layer can achieve lattice matching.

The light-emitting layer having a multiphase structure made of an indium-containing compound semiconductor as described above indicates that the light-emitting layer is composed of a plurality of domains or phases having different indium compositions or concentrations. 10-5
No. 6202). In the light emitting layer having a multiphase structure, a phase having a large spatial occupancy is defined as a main phase (matrix p
hase). Some of the main phases exist in the form of fine crystal grains or the like. For example, there is a microcrystal that exists in the form of a quantum dot (dot) having a diameter of several nm to several tens nm. This is called the dependent phase (su
bsidaryphase). The advantage of forming the light-emitting layer from a group III nitride semiconductor layer having a multiphase structure is that high-intensity light emission is obtained (see Japanese Patent Application Laid-open No.
0-56202). The dependent phase typically has a higher indium composition or concentration as compared to the main phase. In general, the indium composition or concentration differs between the dependent phases.

In the light emitting layer having a multiphase structure, secondary light emission occurs in addition to main light emission mainly due to the difference in indium composition ratio or concentration of the subordinate phase scattered subordinately in the main phase. There are cases. When secondary light emission occurs, light emission lacking in monochromaticity is brought about, which is inconvenient. Such secondary light emission can be avoided by achieving a uniform size (volume) of the dependent phase through a cooling process with an appropriate cooling rate after the growth of the light emitting layer. (JP-A-10-313133).

In the second embodiment, the cladding layer is made of a group III nitride semiconductor lattice-matched to the main phase having a multiphase structure. III-V lattice-matched to a sub-phase with a small volume that occupies spatially in the multi-phase structured light-emitting layer
Even if the cladding layer is formed from a group III compound semiconductor, a cladding layer exhibiting sufficiently satisfactory lattice matching with the entire light emitting layer cannot be formed. In addition, the dependent phase is
Due to the large indium composition ratio, the band gap (band)
gap) is small. Therefore, when the cladding layer is made of a group III nitride semiconductor lattice-matched with the dependent phase, the difference in the band gap with respect to the main phase may be smaller than that with the dependent phase. For this reason, a sufficient cladding effect may not be exerted on the main phase in some cases. On the other hand, from a group III nitride semiconductor that forms a lattice match with the main phase, the light emitting layer is mainly composed of the main phase, so that a cladding layer that generally has good lattice matching for light emission can be formed. In addition, III-V which exerts a cladding action on the basis of the main phase having a larger band gap than the dependent phase.
If the cladding layer is made of a group III compound semiconductor, the cladding function can also be performed on the subordinate phase. Therefore, in the second embodiment of the present invention, the cladding layer is made of a III-V compound semiconductor lattice-matched to the main phase of the light emitting layer having a multiphase structure. The cladding layer referred to here is a cladding layer that is bonded to one surface of the light emitting layer in a light emitting portion having a single hetero structure. In the light emitting portion having a double hetero (DH) junction structure, it refers to upper and lower cladding layers joined to both surfaces of the light emitting layer.

In the third embodiment of the present invention, the current diffusion layer provided on the light emitting portion is formed by using the III that constitutes the upper cladding layer.
It is made of a group III-V compound semiconductor containing phosphorus (P) or arsenic (As) as a constituent element, which lattice-matches with a group nitride semiconductor. For example, n-type or p-type GaN _0.97
A current diffusion layer of n-type or p-type GaN _0.97 P _0.03 is also provided on the upper cladding layer of P _0.03 (lattice constant = 4.538 °). The conduction types of the upper cladding layer and the current spreading layer are matched. N-type or p-type GaN
_An n-type or p-type current diffusion layer is formed from boron phosphide (BP: lattice constant = 4.538 °) lattice-matched to the upper cladding layer made of _0.97 P _0.03 . The current spreading layer made of a material lattice-matched to the upper cladding layer becomes a high-quality crystal layer having a low density of crystal defects such as misfit dislocations generated due to lattice mismatch. For this reason, it is possible to suppress the element driving current from flowing short-circuited and locally to the light emitting portion via crystal defects such as dislocations. Further, the driving current can be diffused over a wide area of substantially the entire surface of the light emitting section, and the light emitting area can be expanded. In the present invention, the lattice mismatch between the upper cladding layer and the current diffusion layer is ± 1%, preferably ± 1%.
It is sufficient that the lattice matching is performed within the range of 0.5%, and the composition of the cladding layer or the current diffusion layer may vary within the range where the lattice matching is performed in the above range.

The current diffusion layer supplies an element driving current to the light emitting portion.
A low resistance layer that can be evenly distributed over a wide area is preferred.
New 5 × 10 in terms of carrier concentration¹⁷cm^-3that's all
And more preferably 1 × 10¹⁸cm^-3About 1 × 10
²⁰cm^-3The following is assumed. About 1 × 10 ²⁰cm^-3Higher than
Impurities were excessively doped to achieve carrier concentration
The crystal layer is the source of doping impurities and the constituent atoms of the crystal layer.
Includes distortions and dislocations mainly caused by differences in element radii
It will be. The device drive current passes through crystal defects such as dislocations
It flows into the light emitting part in a short-circuit, expanding the light emitting area
It hinders you from doing so. Current spreading layer for forming ohmic electrode
Consider the configuration provided as a layer that also serves as the contact layer of
Then, the thickness of the current spreading layer is approximately 20 nm or more.
Is desirable. With a thin layer less than about 20 nm, ohmic
The metal material that forms the contact electrode enters the light-emitting section,
It may come into direct contact with the constituent layers. others
Therefore, the element driving current diffuses in the current diffusion layer
Instead of flowing through the light-emitting part,
This causes a disadvantage that the light emitting area is not sufficiently expanded.
In order to keep the electrode from penetrating the constituent material into the current diffusion layer
In addition, it is more preferable that the thickness of the current diffusion layer be about 50 nm or more.
desirable. Multiplied value of carrier concentration and layer thickness of current diffusion layer
(= N × D) is larger, the obtained current diffusion effect is
large. In other words, the carrier concentration (N: cm)^-3)
Is higher, the thickness (D) of the current spreading layer is substantially the same even when the layer is thinner.
And the like, and the effect of current diffusion can be obtained.

In order to efficiently extract the light emitted from the light emitting layer to the outside, it is desirable that the light emitting layer is made of a material having a larger band gap than the light emitting wavelength. III
-In a group V compound semiconductor, a semiconductor crystal in which the group V constituent element is phosphorus (P) or arsenic (As) has a higher forbidden width than a crystal in which antimony (Sb) is a constituent element. (Iwao Teramoto, "Introduction to Semiconductor Devices")
(March 30, 1995, first edition published by Baifukan Co., Ltd., 28
Page). Therefore, phosphorus (P) or arsenic (As) is converted to V
From the group III-V compound semiconductor contained as a group-constituting element, a current diffusion layer also serving as a window layer for transmitting light emission to the outside can be conveniently formed.

In the fourth embodiment of the present invention, in particular, the clad layer is made of gallium indium nitride (Ga _X In ₁ -XN) mainly composed of cubic crystals. In this case, it is preferable that the current diffusion layer is formed of boron nitride phosphide (BN _1-X P _X ). Mainly cubic means that the volume occupied by the cubic is about 90% or more of the whole. The other component is hexagonal G
aInN crystal. The volume occupancy of the cubic crystals in the crystal layer can be analyzed using, for example, a precise X-ray diffraction method. Range, 0.94 ≦ X ≦ In the Ga _X In _1-X N where the lattice constant of the cubic Ga _X In _1-X N and cubic BN _1-X P X matches
1, and in BN _1-X P _X , 0.97 ≦
X ≦ 1. From the crystal layer having a lattice matching relationship with the cladding layer, a high-quality current diffusion layer having a small crystal defect density such as misfit dislocation can be formed. For this reason, a current spreading layer having excellent crystallinity can be formed, so that the short-circuit flow of the element driving current to the light emitting portion is suppressed, and the effect is obtained that the driving current is spread evenly over substantially the entire surface of the light emitting portion. Is done.

In the fifth embodiment of the present invention, in particular, the cladding layer is made of gallium indium nitride (Ga _x In ₁ -xN) mainly composed of cubic crystals. In this case, the current spreading layer is made of boron arsenide (BN _1-x As _x ) and
It is preferable to obtain a group II nitride semiconductor LED. The range in which the lattice constants of cubic Ga _X In _{1 -X} N and cubic BN _{1 -X} As _X match is 0.43 ≤ X ≤ Ga _X In _{1 -X} N
1, and 0.77 in BN _1-X As _X
≦ X ≦ 1. BN lattice-matched with cladding layer
_{From 1-X} As _X , a good quality current spreading layer can be constructed.
This is effective in suppressing the short-circuit flow of the element driving current to the light emitting unit and diffusing a uniform driving current over substantially the entire surface of the light emitting unit.

In the sixth embodiment of the present invention, the cladding layer is made of gallium nitride phosphide (GaN _0.97 P _0.03 ) mainly composed of cubic crystals having a nitrogen composition ratio of 0.97. In this case, it is preferable to obtain a group III nitride semiconductor LED by forming the current diffusion layer from boron phosphide (BP). Boron phosphide (BP) is a zinc-blende-type crystal (lattice constant = 4.538 °) that lattice-matches with GaN _0.97 P _0.03 , so that current diffusion that is convenient for diffusing current for driving the device in a plane is convenient. Layers can be configured. Further, BP is a cubic crystal, and has an advantage that a crystal layer having a carrier concentration suitable for the current diffusion layer can be easily obtained from its band structure.

In the seventh embodiment of the present invention, the cladding layer is made of gallium arsenide (GaN _0.98 As _0.02 ) mainly composed of cubic crystals having a nitrogen composition ratio of 0.98. In this case, it is preferable to obtain the group III nitride semiconductor LED by forming the current diffusion layer from boron phosphide (BP). The lattice constant of cubic GaN _0.98 As _0.02 is 4.5.
38 °), and a high-quality current diffusion layer which promotes planar diffusion of a driving current from a BP crystal having a lattice matching relationship can be stacked thereon.

On the other hand, BP has a band gap of about 2.0 at room temperature.
It is an indirect transition type semiconductor having an eV (see the above “General Description of Semiconductor Devices”, page 28), and therefore does not sufficiently transmit, for example, blue light having a wavelength of 450 nm or green light having a wavelength of 520 nm. . Therefore, BP
In an LED of a system in which the crystal layer is arranged as a current diffusion layer in the direction of light emission, it is preferable that the thickness of the BP current diffusion layer is generally less than 100 nm. As mentioned above,
As the thickness of the current spreading layer is reduced, the carrier concentration is appropriately adjusted.
If it is increased, the effect of current spreading can be obtained. In the BP crystal, due to the superiority of the band structure in which the valence band is constricted (Toshiaki Ikoma and Hideaki Ikoma, “Introduction to Basic Properties of Compound Semiconductors” (September 10, 1991,
The first edition published by Baifukan Co., Ltd., p. 17), a p-type and n-type crystal layer with a high carrier concentration can be easily obtained. In particular, in the high-temperature BP buffer layer grown through the low-temperature BP buffer layer as described in the present invention, high-concentration impurity doping can be easily achieved.

The buffer layer, the lower and upper cladding layers, the light emitting layer and the current spreading layer according to the present invention are made of metal organic chemical vapor deposition (MOCVD), halogen (halogen).
Vapor phase epitaxy (VPE) method, hydride (hydrid)
e) VPE method, molecular beam epitaxial growth method (MBE)
Method) or the like. For example, when forming a BP crystal layer serving as a current diffusion layer using a triethyl boron ((C ₂ H ₅ ) ₃ B) / phosphine (PH ₃ ) / hydrogen (H ₂ ) reaction system, a temperature of about 900 ° C. About 1200 ° C. is suitable. When grown at a higher temperature, besides the monomeric BP, for example, the chemical formula B
Multimeric BP represented by ₁₃ P ₂ is easily formed,
This is inconvenient for obtaining a P single crystal layer. A GaN _0.97 P _0.03 crystal layer that achieves lattice matching with BP can be grown preferably in substantially the same temperature range.

By laying positive and negative ohmic electrodes on the upper surface and the lower surface (back surface of the Si substrate) of the laminated structure provided with the light emitting portion according to the present invention, an LED such as an LED can be obtained.
Can be configured. In the laminated structure for n-side-up type applications, the substrate is a p-type Si single crystal and the upper surface is an n-type current diffusion layer, so that a positive (positive) ohmic electrode is provided on the back surface of the substrate and a negative (negative) An LED is formed by providing an ohmic electrode on the current spreading layer. In the stacked structure for the p-side-up type application, an n-type ohmic electrode is provided on the reverse side of the Si substrate,
An LED is formed by providing a p-type ohmic electrode on the upper surface. In order to reduce the contact resistance of the ohmic electrode, a highly conductive contact layer can be provided on the current diffusion layer. In this case, the ohmic electrode is laid on the contact layer. When the contact layer is made of a material lattice-matched to the current diffusion layer and made of a material having a band gap larger than the transition energy corresponding to the emission wavelength, a group III nitride having low input resistance and excellent light transmission to the outside of light emission is provided. Material semiconductor LE
D is obtained.

[0039]

The cladding layer sandwiching the light emitting layer made of an indium-containing group III nitride semiconductor has excellent crystallinity with few crystal defects such as misfit dislocations caused by lattice mismatch from the lattice matching with the light emitting layer. It has an effect of providing a light emitting layer.

A group III nitride semiconductor lattice-matched to a group III nitride semiconductor constituting a main phase of a light emitting layer having a multiphase structure composed of a plurality of phases having different indium composition ratios (indium concentrations). Constitutes a barrier layer serving as an effective potential barrier for both the main phase and the dependent phase of the light emitting layer.

A current diffusion layer made of a III-V compound semiconductor containing phosphorus (P) or arsenic (As) as a constituent element, which lattice-matches with a group III nitride semiconductor constituting a cladding layer, has a current for driving an element. Has a function of diffusing the light into the light emitting portion in a planar manner.

In particular, the current diffusion layer composed of a III-V compound semiconductor containing phosphorus (P) or arsenic (As), which lattice-matches with the cladding layer, uniformly diffuses the element driving current to the light emitting portion in a plane. It has the effect of promoting the expansion of the light emitting area.

[0043]

EXAMPLES (Example 1) Boron phosphide (B
P) Gallium phosphide mixed crystal (G
Group III nitride having a lattice-matched light emitting portion composed of aN _1-X P _X , where 0 ≦ X ≦ 1 and gallium indium nitride (Ga _X In _{1 -X} N, where 0 ≦ X ≦ 1) Semiconductor LED
The present invention will be specifically described by way of an example. FIG. 1 is a schematic cross-sectional view of the LED 10 according to the first embodiment.

As the substrate 101, a boron (B) -doped p-type (111) -Si single crystal was used. On the substrate 101, a low-temperature buffer layer 102 made of boron phosphide (BP) was deposited. The low-temperature buffer layer 102 is made of triethyl boron ((C ₂ H ₅ ) ₃
B) / phosphine (PH ₃ ) / hydrogen (H ₂ ) based atmospheric pressure MOC
It was grown at 350 ° C. by the VD method. The thickness of the buffer layer 102 was about 14 nm. On the surface of the low-temperature buffer layer 102, 950 is applied using the MOCVD vapor deposition means described above.
A p-type BP layer doped with magnesium (Mg) at ° C. was laminated as a high-temperature buffer layer 103. The doping source magnesium bis - using cyclopentadienyl magnesium _{(bis- (C 5 H 4)} 2 Mg). The carrier concentration of the high-temperature buffer layer 103 was about 7 × 10 ¹⁸ cm ⁻³ . The layer thickness was 250 nm.

On the high temperature buffer layer 103, boron phosphide (B
The phosphorus (P) composition ratio lattice-matching with P) is 0.03 (= 3
%) Magnesium doped p-type gallium phosphide
(GaN_0.97P_0.03) Layer as lower cladding layer 104
Laminated. Cubic GaN_0.97P _0.03The layer is trimethylga
Lium ((CH_Three)_ThreeGa) / PH_Three/ Ammonia (N
H_Three) / H_TwoGrown at 1000 ° C by MOCVD under normal pressure
I let it. The carrier concentration of the lower cladding layer 104 is about 8 ×
10¹⁷cm^-3And the layer thickness was about 12 nm.

On the lower cladding layer 104, a thickness of about 1
N-type gallium indium nitride (Ga _1-X
A light emitting layer 105 made of In _x N) was laminated. The indium composition ratio (= X) is equal to the G of the lower cladding layer 104.
The aN _0.97 P _0.03 layer was set to 0.10.
The light-emitting layer 105 was grown at 830 ° C. by a normal pressure MOCVD method based on (CH ₃ ) ₃ Ga / cyclopentadienyl indium (C ₅ H ₅ In) / PH ₃ / NH ₃ / H ₂ .

On the surface of the light emitting layer 105, (CH_Three)_ThreeG
a / PH_Three/ NH_Three/ H_Two10 by normal atmospheric pressure MOCVD
The upper cladding layer 106 was laminated at 00 ° C. Upper crack
Layer 106 is made of cubic Ga._0.90In_0.10N light emitting layer 10
(Si) doped n-type GaN lattice matched to 5_0.97P
_0.03It consisted of layers. Carrier of upper cladding layer 106
The concentration is about 8 × 10¹⁷cm^-3And the layer thickness is 240 nm
Was. Cubic p-type GaN _0.97P_0.03Lower cladding 104
And cubic Ga_0.90In_0.10N light emitting layer 105 and cubic n
GaN_0.97P_0.03Lattice alignment from upper cladding layer 106
Light emitting unit 108 having a combined pn junction type double hetero junction structure
Was configured.

On the upper cladding layer 106, GaN _0.97
A current diffusion layer 107 made of n-type boron phosphide (BP) lattice-matched to the P _0.03 layer was laminated. The Si-doped BP layer forming the current diffusion layer 107 is (C ₂ H ₅ ) ₃ B / PH ₃ / H ₂
It was grown at 1000 ° C. by a system normal pressure MOCVD method.
The thickness of the current diffusing layer 107 was about 50 nm, The carrier concentration was set at about 1 × 10 ¹⁹ cm ^-3.

On the back surface of the p-type Si single crystal substrate 101, a p-type ohmic (Ohmi) made of aluminum (Al) is provided.
c) The electrode 109 was formed. Further, an n-type ohmic electrode 110 made of gold (Au) was arranged at the center of the surface of the current diffusion layer 107. The diameter of the n-type ohmic electrode 110 was about 130 μm. After that, Si used as the substrate 101
The single crystal is cut in a direction parallel to and perpendicular to the [211] direction, and an LED chip (chi) having a side of about 300 μm.
p) was 10.

LE between both ohmic electrodes 109-110
D drive current was passed. The current-voltage (IV characteristics) showed normal rectification characteristics based on good pn junction characteristics of the light emitting unit 108. The forward voltage (V) determined from the IV characteristics
f) was about 3.1 V (however, the forward current was 20 mA). The reverse voltage was about 15 V (however, the reverse current was 10 μA). 20 mA in the forward direction (m
When the operating current of A) is passed, the central emission wavelength is about 4
Blue light having a wavelength of 60 nm was emitted. The half width of the emission spectrum was about 18 nm. The light emission intensity in a chip state measured using a general integrating sphere was about 16 microwatts (μW), and a Group III nitride semiconductor LED with high light emission intensity was provided.

(Embodiment 2) In the laminated structure described in Embodiment 1, only the upper clad layer (106 in FIG. 1) is changed to a gallium arsenide nitride (GaN _0.98 As _0.02 ) layer.
The other constituent layers were the same as in Example 1 to form an LED.
The arsenic composition ratio of the n-type gallium arsenide nitride forming the upper clad layer is 2% (= 0.538), which is the same lattice constant (= 4.538 °) as the Ga _0.90 In _0.10 N light emitting layer and the BP current diffusion layer.
02). The carrier concentration of the upper cladding layer was about 2 × 10 ¹⁸ cm ⁻³ , and the layer thickness was about 200 nm.

Otherwise, the L was formed in the same manner as in Example 1.
When a forward current of 20 mA was passed between the positive and negative ohmic electrodes of the ED, blue light having a center wavelength of about 460 nm was emitted. The forward voltage (Vf) was about 3.1 V. The light emission intensity in a chip state is about 15 μW,
A high emission intensity group III nitride semiconductor LED has been provided.

(Embodiment 3) LED 2 according to Embodiment 3
FIG. 2 shows a schematic cross-sectional view taken along line 0 of FIG. On a phosphorus (P) -doped n-type (111) -Si single crystal substrate 201, diborane (B
_{2 H 6) / (CH 3} ) 3 Ga / arsine (AsH ₃₎ / H ₂ system arsenide boron gallium at 400 ° C. under reduced pressure MOCVD method (B
A low-temperature buffer layer 202 composed of _X Ga _1-X As, where 0 ≦ X ≦ 1) was laminated. The composition ratio (= X) of boron (B) is S
It was set to 0.25 which lattice-matched to the i single crystal. Low temperature buffer layer 2
02 was grown under reduced pressure of about 1.3 × 10 ⁴ Pascal (Pa). The layer thickness of the low-temperature buffer layer 202 was about 15 nm.

According to observation by a cross-sectional transmission electron microscope (TEM) method, as-grown (as-grown) film is formed.
In the B _0.25 Ga _0.75 As low temperature buffer layer 202 in the n) state,
The upper region approximately 3 nm from the bonding surface with the Si single crystal substrate 201 was a single crystal. In addition, B _0.25 Ga
_0.75 As low temperature buffer layer 202 and n-type Si single crystal substrate 201
No good peeling was observed and good adhesion was maintained.
The upper part of the low-temperature buffer layer 202 was mainly composed of an amorphous body.

[0055] On B _0.25 Ga _0.75 As low-temperature buffer layer 202, using the above reduced pressure MOCVD reaction system, 950 ° C.
-Doped B with boron composition (= X) with composition gradient
_{An X} Ga _{1 -XP} high temperature crystal layer 203 was laminated. The composition ratio of boron (B) is 0.0 in the increasing direction of the thickness of the high-temperature buffer layer 203.
It was increased linearly from 2 to 1.0. That is, the surface of the composition gradient high-temperature buffer layer 203 was a boron phosphide (BP) layer.
The composition gradient of boron (B) was applied by uniformly increasing the supply amount of diborane to the MOCVD reaction system over time and decreasing the supply amount of trimethylgallium uniformly. About 1 layer thickness
7 nm. The pressure of the reaction system during the growth of the high-temperature buffer layer 203 was set to about 1.3 × 10 ⁴ Pa. B _X Ga _1-X P compositional gradient (X = 0.02 → 1.0) at the time of growth of the buffer layer 203, doped with Si using disilane (Si ₂ H ₆₎ -H ₂ mixed gas. Carrier concentration is about 1 × 10 ¹⁸ c
m ^-3 was set. According to the analysis by the X-ray diffraction analysis method, the high-temperature crystal layer 203 has a (111) -oriented cubic B _X Ga
_{1-X P (X = 0.02} → 1.0) were found to be single crystal layer.

[0056] After completing the formation of the high-temperature buffer layer 203 was B _X Ga _1-X P compositional gradient layer, most of the B _{0. 25} Ga _0.75 As low-temperature buffer layer 202 inside of the amorphous body, as-gr
The single crystal was converted to a single crystal based on the single crystal layer existing in the boundary region with the Si single crystal substrate 201 in the down state. Also, B
_X Ga _{1 -X} P (X = 0.02 → 1.0) High temperature buffer layer 203
Is B _0.25 Ga _0.75 A having a composition lattice-matched with the Si single crystal.
s (lattice constant = 5.431 °) low-temperature buffer layer 20
2, a continuous film without peeling was obtained.

On the high temperature buffer layer 203, (CH_Three)_ThreeGa
/ C_FiveH_FiveIn / NH_Three/ H_Two9 by the reduced pressure MOCVD method
At 00 ° C., the indium composition ratio is set to 1% (= 0.01).
N-type gallium nitride-indium mixed crystal (Ga_0.99In
_0.01The lower cladding layer 204 made of N) was provided. beneath
The carrier concentration of the cladding layer 204 is about 5 × 10¹⁸cm^-3
And the layer thickness was about 300 nm. Lower cladding layer 2
04 on (CH_Three)_ThreeGa / C_FiveH_FiveIn / NH_Three/ H_Two
At 900 ° C by low-pressure MOCVD method.
Indium composition ratio is 0.01, average indium composition ratio
Is provided with an n-type light emitting layer 205 having a multiphase structure of about 0.06.
Was. The layer thickness of the light emitting layer 205 was about 80 nm. Multi-phase structure
On the light emitting layer 205, the above MOCVD reaction system is used.
And p-type Ga_0.99In_0.01Upper cladding layer made of N
The light emitting section 208 having a pn junction type DH structure
Was configured. The carrier concentration of the upper cladding layer 206 is 7
× 10 ¹⁷cm^-3And the layer thickness was about 10 nm.

[0058] p-type Ga _0.99 In _0.01 N upper cladding layer 2
On p. 06, a p-type boron nitrided phosphide (BN _{1 -X} P _x , where 0.97 ≦ X ≦ 1) layer was laminated as a current diffusion layer 207. The nitrogen composition ratio is the same as the lattice constant of the upper cladding layer (=
4.515 °).

On the back surface of n-type Si single crystal substrate 201, an n-type ohmic (Ohmi) made of aluminum (Al) is provided.
c) An electrode 209 was formed. In addition, a p-type ohmic electrode 210 made of gold (Au) was arranged at the center of the surface of the current diffusion layer 207. The diameter of the p-type ohmic electrode 210 was about 130 μm. After that, the Si used as the substrate 201 was formed.
The single crystal is cut in a direction parallel and perpendicular to the [211] direction, and an LED chip (chi) having a side of about 260 μm
p) 20.

LE between both ohmic electrodes 209-210
D drive current was passed. The current-voltage (IV characteristics) showed normal rectification characteristics based on good pn junction characteristics of the light emitting section 208. The forward voltage (V) determined from the IV characteristics
f) was about 3.5 V (however, the forward current was 20 mA). The reverse voltage was about 15 V (however, the reverse current was 10 μA). 20 mA in the forward direction (m
When the operating current of A) is passed, the central emission wavelength is about 4
Blue light of 10 nm was emitted. The half width of the emission spectrum was about 22 nm. The light emission intensity in a chip state measured using a general integrating sphere was about 12 microwatts (μW), and a Group III nitride semiconductor LED with high light emission intensity was provided.

(Embodiment 4) In the laminated structure described in Embodiment 3, only the current spreading layer (207 in FIG. 2) is made of boron arsenide (BN ₁ -x As _x , where 0.77 ≦ X). .Ltoreq.1), and the other constituent layers were the same as in Example 3 to form an LED. The arsenic composition ratio of the magnesium (Mg) -doped p-type boron arsenide constituting the current diffusion layer has the same lattice constant (= 4.515 °) as that of Ga _0.99 In _0.01 N constituting the main phase of the light emitting layer and the upper cladding layer. It was set to 77% (= 0.77). The carrier concentration of the current diffusion layer is about 2 × 10 ¹⁸ c
m ⁻³ and a layer thickness of about 200 nm.

Otherwise, the L was formed in the same manner as in Example 3.
When a forward current of 20 mA was passed between the positive and negative ohmic electrodes of the ED, blue light having a center wavelength of about 410 nm was emitted. The forward voltage (Vf) was about 3.3V. The light emission intensity in a chip state is about 11 μW,
A high emission intensity group III nitride semiconductor LED has been provided.

[0063]

According to the present invention, a buffer layer made of a group III-V compound semiconductor containing phosphorus (P) or arsenic (As) as a constituent element is formed on the surface of a Si single crystal substrate.
Since a light-emitting portion having a pn junction type DH junction structure is provided from a group III nitride semiconductor layer having a lattice matching relationship, deterioration of crystallinity due to lattice mismatch is avoided, and high quality III
The light emitting section can be composed of the group III nitride semiconductor layer.
In addition, since the current spreading layer provided on the light emitting unit is made of a group III-V compound semiconductor lattice-matched to the cladding layer constituting the light emitting unit, an effect of diffusing the LED drive current over a wide range of the light emitting unit can be obtained. And a group III nitride semiconductor light emitting diode having high light emission intensity.

In particular, when the cladding layer is made of a group III nitride semiconductor lattice-matched to the group III nitride semiconductor which is the main phase of the light emitting layer having a multiphase structure composed of a plurality of phases having different indium composition ratios, It is possible to form the cladding layer from a group III nitride semiconductor layer having good crystallinity by lattice matching with the layer and to form a cladding layer that reliably acts as a barrier (cladding) on the multi-phase structured light emitting layer. Accordingly, it is possible to provide a group III nitride semiconductor light emitting diode having high light emission intensity.

Further, phosphorus (P) or arsenic (A) which lattice matches with the group III nitride semiconductor constituting the cladding layer
When the current diffusion layer is formed from a group III-V compound semiconductor containing s) as a constituent element, a current diffusion layer that can diffuse the LED drive current over the entire area of the light emitting section can be formed, and high emission intensity can be obtained. A group III nitride semiconductor light emitting diode can be provided.

In particular, gallium indium nitride (Ga _x In ₁ -xN, which is mainly composed of cubic crystals, provided that 0 ≦ X ≦ 0.9
When the current spreading layer is made of boron nitride nitride (BP _1-x N _x , where 0 ≦ X ≦ 0.03) with respect to the cladding layer made of (0), it is convenient for diffusing the LED driving current over a wide range of the light emitting portion. In addition, the current diffusion layer can be formed from a group III nitride semiconductor layer having a small density of crystal defects due to lattice mismatch and excellent crystallinity. A semiconductor light emitting diode can be provided.

In particular, gallium indium nitride mainly composed of cubic crystals (Ga _X In _{1 -X} N: 0.43 ≦ X ≦ 1)
When the current spreading layer is made of boron nitride arsenide (BAs _1−X N _x , where 0 ≦ X ≦ 0.23), a grid that is convenient for diffusing the LED drive current over a wide area of the light emitting portion is formed. The current diffusion layer can be composed of a group III nitride semiconductor layer having a small density of crystal defects due to mismatch and excellent in crystallinity, and thus has an effect of expanding a light emitting area, and is a group III nitride semiconductor light emitting diode. Can be provided.

In particular, gallium phosphide (GaN _0.97 P) mainly composed of cubic crystals having a nitrogen composition ratio of 0.97
_When the current spreading layer is made of boron phosphide (BP) for the cladding layer made of _0.03 ), the density of crystal defects caused by lattice mismatch, which is favorable for diffusing the LED driving current over a wide area of the light emitting portion, is small, and the crystallinity is low. The current spreading layer can be composed of a group III nitride semiconductor layer excellent in
This is effective in expanding the light emitting area, and can provide a group III nitride semiconductor light emitting diode.

In particular, gallium arsenide nitride (GaN _0.98 A) mainly composed of cubic crystals having a nitrogen composition ratio of 0.98
s _0.02 ), when the current spreading layer is made of boron phosphide (BP), the density of crystal defects due to lattice mismatch, which is favorable for diffusing the LED driving current over a wide range of the light emitting portion, is small. III with excellent properties
The current diffusion layer can be formed from the group-III nitride semiconductor layer, which is effective in expanding the light-emitting area, and can provide a group-III nitride semiconductor light-emitting diode.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an LED according to Examples 1 and 2.

FIG. 2 is a schematic sectional view of an LED according to Examples 3 and 4.

[Explanation of symbols]

 10, 20 LED 101, 201 Si single crystal substrate 102, 202 Low temperature buffer layer 103, 203 High temperature buffer layer 104, 204 Lower cladding layer 105, 205 Light emitting layer 106, 206 Upper cladding layer 107, 207 Current diffusion layer 108, 208 Light emission Part 109, 209 Back ohmic electrode 110, 210 Front ohmic electrode

Claims (10)

[Claims] 1. A silicon (Si) single crystal substrate, a buffer layer provided on the surface of the substrate and made of a group III-V compound semiconductor containing phosphorus (P) or arsenic (As) as a constituent element, and the buffer layer A pn-junction double heterojunction structure in which a light-emitting layer made of indium-containing group III nitride semiconductor provided on the layer is sandwiched between cladding layers made of p-type and n-type group III nitride semiconductors lattice-matched to the light-emitting layer A light emitting unit,
A group III nitride semiconductor light emitting diode comprising at least a current diffusion layer made of a group III-V compound semiconductor provided on the light emitting part. 2. A group III lattice-matching the cladding layer to a group III nitride semiconductor constituting a main phase of a light emitting layer having a multiphase structure composed of a plurality of phases having different indium composition ratios (indium concentrations). The group III nitride semiconductor light emitting diode according to claim 1, wherein the light emitting diode is made of a nitride semiconductor. 3. A current diffusion layer comprising a group III-V compound semiconductor containing phosphorus (P) or arsenic (As) as a constituent element, which lattice-matches with a group III nitride semiconductor forming a cladding layer. The group III nitride semiconductor light emitting diode according to claim 1 or 2, wherein 4. A gallium nitride comprising a cladding layer of the cubic mainly indium _{(Ga X In 1-X N} , where 0.94
≦ X ≦ 1), wherein the group III nitride semiconductor light-emitting diode according to claim 3, wherein 5. The method according to claim 1, wherein the current spreading layer is formed of boron nitride phosphide (BN).
5. The group III nitride semiconductor light emitting diode according to claim 4, wherein _1-X P _{x is} provided, wherein 0.97 ≦ X ≦ 1). 6. A gallium indium nitride (Ga _X In ₁ -XN, 0.43
≦ X ≦ 1), wherein the group III nitride semiconductor light-emitting diode according to claim 3, wherein 7. The current spreading layer is made of boron arsenide (BN _1-X A
7. The group III nitride semiconductor light-emitting diode according to claim 6, wherein s _x satisfies 0.77 ≦ X ≦ 1). 8. A nitride comprising a cubic crystal as a main component in a cladding layer.
Gallium phosphide (GaN _0.97P_0.03)
The group III nitride semiconductor device according to claim 3, wherein
Photo diodes. 9. Group III nitride semiconductor light emitting diode according to claim 3, characterized in that consisted nitride gallium arsenide comprising a cladding layer of the cubic mainly (GaN _{0. 98} As _0.02). 10. The II according to claim 8, wherein the current spreading layer is made of boron phosphide (BP).
Group I nitride semiconductor light emitting diode.