JP2000004068A - Semiconductor light emitting device - Google Patents

Abstract

(57) [Summary] [Problems] Band barrier differences ΔEc, ΔEv at a heterojunction
To provide a short wavelength semiconductor light emitting element having a high characteristic temperature (operating stably even at a high temperature (for example, about room temperature)) and high luminous efficiency. SOLUTION: N as a group V element is formed on a semiconductor substrate 11.
A semiconductor light emitting device using a group III-V mixed crystal semiconductor layer containing (nitrogen) and P (phosphorus) as an active layer 15, wherein the active layer 15 is Ga _x2 In _1-x2 N _z2 P _1-z2 ( 0 ≦ x2 ≦ 1,0
<Z2 <1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser for optical writing, a semiconductor laser for reading, a light emitting diode,
Used for photodiodes, etc.
The present invention relates to a semiconductor light emitting device using a group III-V mixed crystal semiconductor layer containing (nitrogen) and P (phosphorus) as an active layer.

[0002]

2. Description of the Related Art Conventionally, AlGaIn has been used as a material for a high-intensity green-red light emitting diode used for a color display and a visible semiconductor laser used for optical writing and the like.
Research and development of P-based materials are underway. AlGaInP
The system material is the largest direct transition type material among the group III-V semiconductors lattice-matched to the GaAs substrate, and has a band gap energy of about 2.3 eV (wavelength 540
nm).

However, AlGaInP-based materials are:
When a heterojunction is formed, the conduction band discontinuity between the active layer and the cladding layer (or guide layer) having a larger bandgap energy than that of the active layer provided to confine carriers therein is small (the conduction band band). Since the offset ratio is small), the structure is such that injected carriers (electrons) easily overflow from the active layer to the cladding layer.
Due to this, there is a problem that the temperature dependence of the oscillation threshold current of the semiconductor laser is large and the temperature characteristics are poor.
In addition, when a composition having a wider gap is used for the active layer or a quantum well structure is used for shortening the wavelength, carrier overflow occurs mainly due to a small band offset ratio described above, resulting in a good temperature. It has been difficult to realize a light emitting element having characteristics.

As described above, in the AlGaInP-based material, the conduction band discontinuity at the heterojunction is small, and carriers injected into the active layer easily overflow into the cladding layer (or the guide layer). Is difficult to obtain. This is particularly noticeable when the emission wavelength is shortened by the quantum well structure. In order to improve this characteristic, for example, reference 1 “Japanese Patent Laid-Open No.
No. 86, an attempt has been made to reduce the carrier overflow by providing a multiple quantum barrier layer (MQB). Along with this, for example, Reference 2 “H
amada etal.Electronics Letter, Vol.28 No.19 (19
92) P1834 ", a compression quantum well layer in which a quantum well layer is strained to reduce a threshold current has been proposed. That is, Document 2 reports continuous oscillation at an oscillation wavelength of 615 nm at room temperature due to a structure in which a multiple quantum barrier (MQB) and a compression-strained multiple quantum well layer of (Al _0.08 Ga _0.92 ) _0.45 In _0.55 P are combined. However, the temperature characteristics of this device are very poor.

[0005] In addition to the above-mentioned documents, an AlGaInP-based material that obtains an oscillation wavelength of about 600 nm using a substrate other than GaAs (to realize a short-wavelength laser having an oscillation wavelength of 600 nm or less), for example, Document 3 "Japanese Patent Laid-Open No. 6-53602" has been proposed. That is, in this document 3, GaP is used as a substrate, AlGaP is used as a cladding layer on this substrate, a direct transition type GaInP quantum barrier layer and a quantum well are used as an active layer, and an impurity of an isoelectronic trap is used as an active layer. An element doped with N has been proposed. However,
Even in this device, carriers cannot be sufficiently confined in the active layer, and good temperature characteristics cannot be expected.

Further, instead of the AlGaInP-based material,
As a method of realizing a short-wavelength laser of about 00 nm, for example, Japanese Patent Laid-Open No. 7-7223 (Document 4) has been proposed. That is, in this document 4, in order to obtain a visible light emitting element on a Si substrate or a GaP substrate, N
III-V mixed crystal semiconductor material containing (nitrogen), such as In
NSb and AlNSb-based materials have been proposed. The band gap of this mixed crystal is InN, InSb, AlN
And AlSb are estimated linearly. AlN _0.4 S
A composition that lattice-matches with a Si substrate at b _0.6 has a band gap energy of about 4 eV, and a light emitting element up to ultraviolet can be obtained.

However, most of the group III-V mixed crystal semiconductors containing N (nitrogen) as a group V element are in the immiscible region, and it is difficult to grow crystals by normal growth. That is, NE is formed by MBE or MOCVD having a high non-equilibrium
The limit is to add about 10% (nitrogen). Also,
As shown in Document 5, "Japanese Patent Application Laid-Open No. 6-334168", since the electronegativity of N is large in this material system, a large bowing occurs in the band gap of the mixed crystal, and the lattice constant matching with the Si or GaP substrate is generated. Then, on the contrary, the band gap becomes small. For this reason, it is considered that the proposal of Document 4 is difficult to realize.

[0008]

As described above, it is difficult to obtain an oscillation wavelength of about 600 nm even if other material systems are used, and the AlGaInP-based material has insufficient conduction band discontinuity, so that room temperature However, an element having stable temperature characteristics and excellent temperature characteristics has not been obtained.

According to the present invention, the band barrier difference Δ
Ec and ΔEv can be increased as required for laser oscillation, and the characteristic temperature is high (high temperature (for example, about room temperature)).
However, it is intended to provide a short-wavelength semiconductor light-emitting device having stable operation) and high luminous efficiency.

[0010]

In order to achieve the above object, the invention according to claim 1 is directed to a III-V mixed semiconductor containing N (nitrogen) and P (phosphorus) as group V elements on a semiconductor substrate. a semiconductor light emitting device using the crystallized semiconductor layer as an active layer, the active layer is _{Ga x2 in 1-x2 N z2} P 1-z2 (0 ≦ x2 ≦ 1,0 <z2
<1).

According to a second aspect of the present invention, in the semiconductor light emitting device according to the first aspect, the semiconductor light emitting device comprises:
(Al _x3 Ga _1-x3 ) _y3 In _1-y3 P (0 ≦ x3 ≦ 1,0 <y
3 <1) and a Ga _x2 I
Having an intermediate layer made of a III-V group semiconductor not containing Al and N between an active layer made of n _{1 -x2} N _z2 P _{1 -z2} (0 ≦ x2 ≦ 1, 0 <z2 <1) It is characterized by.

According to a third aspect of the present invention, in the semiconductor light emitting device of the second aspect, the intermediate layer is at least a monoatomic layer and is sufficiently thinner than the thickness of the GaInNP active layer. I have.

According to a fourth aspect of the present invention, in the semiconductor light emitting device according to the second or third aspect, the intermediate layer is formed of three or less types of III-V elements not containing Al and N.
It is characterized by being composed of a group III semiconductor.

According to a fifth aspect of the present invention, in the semiconductor light emitting device of the fourth aspect, the intermediate layer is made of a group III-V semiconductor of two kinds of constituent elements not containing Al and N. Features.

According to a sixth aspect of the present invention, in the semiconductor light emitting device according to the third or fourth aspect, a GaAs substrate is used as a semiconductor substrate, and Ga _x4 is used as an intermediate layer.
It is characterized in that an In _1-x4 P mixed crystal semiconductor (0 <x4 <1) is used.

[0016] The invention described in claim 7 is based on claim 3,
The semiconductor light emitting device according to claim 4 or 5, wherein GaAs is used as the semiconductor substrate, and GaP having a thickness less than or equal to a critical thickness at which misfit transition occurs is used as the intermediate layer.

According to an eighth aspect of the present invention, in the semiconductor light emitting device according to the third or fourth aspect, GaP is used as the semiconductor substrate and Ga _x5 In is used as the intermediate layer.
It is characterized in that a _1-x5 P mixed crystal semiconductor (0 <x5 <1) is used.

The invention according to claim 9 is the second invention.
6. The semiconductor light emitting device according to claim 3, wherein the III-V semiconductor intermediate layer is formed at each boundary between the cladding layer or the guide layer and the GaInNP active layer. Layer or guide layer and G
A multi-quantum well structure having a light-emitting portion is formed by a laminated structure in which a III-V group semiconductor intermediate layer is formed at each boundary with the aInNP active layer.

The invention according to claim 10 is the second invention.
The semiconductor light emitting device according to any one of claims 6 to 8, wherein the intermediate layer is disposed only on the substrate side with respect to the active layer.

The invention according to claim 11 is the first invention.
0, the intermediate layer is formed at each boundary between the barrier layer on the substrate side with respect to the GaInNP active layer and the GaInNP active layer, and the barrier layer and the GaI
It is characterized by a multiple quantum well structure having a light emitting portion formed by a laminated structure in which an intermediate layer is formed at each boundary with the nNP active layer.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. The present invention provides a semiconductor light emitting device of 630 nm, 650 nm and shorter wavelength having high luminous efficiency and high characteristic temperature constituted by an AlGaInP-based material and a GaInNP mixed crystal obtained by adding nitrogen thereto as an active layer. It is intended to be realized.

For example, if a mixed crystal semiconductor GaInNAs containing nitrogen (N) is added with a few percent of nitrogen (N) to a conventionally existing III-V semiconductor such as GaInAs, the band gap energy becomes small. At the same time, it is known that the energy of the conduction band and the energy of the valence band decrease.

Further, since the lattice constant is reduced by the addition of nitrogen, it has been reported that oscillations at 1.3 μm and 1.5 μm, which were difficult to obtain using a GaAs substrate, were possible on the same substrate.

The inventor of the present application has found that such an effect is
It has been found that GaInP can be similarly expected. That is, several percent of nitrogen (N) is added to AlGaInP,
It has been found that the band gap energy and the energies of the conduction band and the valence band can both be reduced by using the aInNP mixed crystal. Also, using AlGaInP for the cladding layer or the guide layer (barrier layer),
In a heterojunction using AlGaInNP obtained by adding nitrogen to AlGaInP having the same composition as the cladding layer or the guide layer as the active layer, the valence band energy of the active layer is smaller. Although it cannot be confined in the layer, it has been found that the heterojunction having the same structure causes a large band discontinuity on the conduction band side. In other words, if the composition is appropriately selected, such as using a sufficiently large band gap clad layer or guide layer,
Holes can be confined in the active layer. As such a cladding layer or a guide layer, AlGaInP having an Al composition larger than that of the active layer can be used.

If AlGaInNP is used for the active layer and the band gap is larger than that of this active layer, and if AlGaInP to which nitrogen is not added is used for the cladding layer or the guide layer, the band discontinuity on the conduction band side is large and the characteristic temperature is high. (A device that operates stably even at a high temperature (for example, at a temperature around room temperature)) can be realized.

In other words, in the conventional heterojunction made of AlGaInP, the amount of band discontinuity in the conduction band is insufficient for confining carriers, and the amount of band discontinuity in the valence band is larger than a required value. . That is, the band offset ratio was not an appropriate value. However, if AlGaInNP to which nitrogen is added is used as the active layer, it becomes possible to increase the band discontinuity of the conduction band as described above. Moreover, since the decrease in energy on the valence band side is smaller than that in the conduction band, holes can be confined in the active layer even after nitrogen addition by using an appropriate cladding layer or guide layer as described above. That is, the offset ratio can be improved to a preferable value. Also, a quaternary mixed crystal Al containing Al
In GaInP, the band gap can be changed according to the Al composition ratio, and an active layer having a wide gap can be obtained. Therefore, there is an advantage that the degree of freedom in band design is increased if the active layer is formed by adding nitrogen to the active layer.

In the present invention, the nitrogen concentration at which a mixed crystal band is formed by adding nitrogen is set to 3 × 10 ¹⁹ [c
m ⁻³ ] or more (about 0.1% in the nitrogen group V composition ratio).
3% or more). In addition, conventionally, a method of adding nitrogen as an impurity of an isoelectronic trap to make it a direct transition type is widely known in order to increase the luminous efficiency of an indirect transition type semiconductor such as GaP. The amount (nitrogen concentration) is 3 × 10 ¹⁹ [cm ⁻³ ] or less. When nitrogen is added at a concentration of 3 × 10 ¹⁹ [cm ⁻³ ] or more, the crystal becomes a mixed crystal semiconductor containing nitrogen, and the effect of reducing the energy in the conduction band and the valence band can be sufficiently obtained. The present invention is essentially different from the above-described conventional example in this point.

However, 3 × 1
When nitrogen is added to a concentration of 0 ¹⁹ [cm ⁻³ ] or more, AlG
Experiments by the inventors of the present application have revealed that the crystallinity of aInNP itself is significantly reduced, and it is difficult to obtain good crystallinity. For example, as shown in Example 1 to be described later, irregularities are generated on the crystal surface by adding a small amount of nitrogen to a composition in which the group III composition ratio of Al is 0.1. Such a decrease in crystallinity increases the non-radiative recombination process, and increases the oscillation threshold current value. For this reason, it is difficult to obtain high luminous efficiency in a device using AlGaInNP as an active layer.

On the other hand, the above concentration (3 ×
When nitrogen addition of 10 ¹⁹ [cm ^-3 ]) or more is performed,
No remarkable decrease in crystallinity is observed unlike AlGaInNP. It is considered that the cause of the decrease in crystallinity is that AlGaInNP is a quinary system. This is because the greater the number of constituent elements, the greater the immiscibility and the more difficult the crystal growth. Also, Al
The cause may be that atoms are contained. Al
Is considered to be chemically active and easy to grow three-dimensionally. Therefore, if GaInNP is used as the active layer,
There is a possibility that an element with high luminous efficiency can be obtained. But,
Even in this case, AlGa has been obtained from experiments conducted by the inventor of the present application.
It has been found that it is difficult to realize a light emitting device using InP as a cladding layer or a guide layer.

As described above, according to the present invention, in the III-V mixed crystal semiconductor light emitting device containing N (nitrogen) and P (phosphorus) as group V elements, the active layer is made of Ga _x2 In _1-x2 N _z2. P
_1-z2 (0 ≦ x2 <1, 0 <z2 <1). The active layer _{Ga x2 In 1-x2 N z2} P 1-z2 (0 ≦ x2 <1,0 <z2
By setting <1), light emission in a visible wavelength region can be obtained. Further, by adding nitrogen (N), the band gap energy becomes smaller and the energy in the conduction band and the valence band becomes lower as compared with the case where nitrogen is not added. Therefore, by selecting the composition, a heterojunction having a large conduction band discontinuity and an unconventional arbitrary band offset ratio can be formed. That is,
An element having a high characteristic temperature that operates stably even at a high temperature (for example, a temperature of about room temperature) as compared with the related art can be realized.

As described above, such a group V element includes N
Most of the mixed crystal semiconductors containing in the non-miscible region are very difficult to grow. MOCVD with high non-equilibrium degree
Only a crystal having a slight nitrogen composition can be grown by the method (metal organic chemical vapor deposition) or MBE (molecular beam epitaxy). As the number of constituent elements increases, the mixed crystal semiconductor becomes more immiscible. Even with the same mixed crystal, a mixed crystal having an intermediate composition has higher immiscibility. That is, a binary compound is most likely to grow. The same can be said for a mixed crystal semiconductor containing N in a group V element.
As described above, since AlGaInNP is a quinary mixed crystal, it is difficult to obtain a high-quality crystal. Further, the fact that Al is chemically active and easily grows three-dimensionally makes this difficult.

Accordingly, in the present invention, the number of constituent elements is smaller than that of AlGaInP and Ga containing no Al is used.
Since InNP is used for the active layer, a high-quality crystal can be easily obtained, and the luminous efficiency can be improved. At this time, it is advantageous to select an active layer having a large Ga composition. This is because GaInP having a larger Ga composition can add more nitrogen. Thereby, the effect of sufficiently lowering the energy of the conduction band can be obtained. Further, addition of nitrogen reduces the band gap energy of the mixed crystal, and therefore, it is important to use a composition having a large Ga composition (large band gap energy) even in shortening the wavelength. By selecting an appropriate composition in this way, a light-emitting element having a high characteristic temperature even at a short wavelength emission wavelength can be obtained.

As described above, when nitrogen (N) is added to GaInP containing no Al (assumed to be GaInNP), an active layer having good crystallinity can be obtained. However, AlGaI
In a device in which a GaInNP active layer is directly formed on an nP guide layer or a cladding layer, although the crystallinity is greatly improved, it is difficult to sufficiently increase the luminous efficiency.
This is because at the start of the growth of the GaInNP active layer, Al atoms are contained in the constituent elements on the growth surface. The crystallinity at the heterojunction interface affects the crystallinity of the GaInNP active layer and its upper layer. The inventor of the present application has found that this problem can be solved by separating the AlGaInP guide layer or cladding layer from the GaInNP active layer with a suitable III-V semiconductor layer (intermediate layer) containing no Al and N. I found further.

That is, the present invention further provides (Al _x3 G
a _1-x3 ) _y3 In _1-y3 P (0 ≦ x3 ≦ 1, 0 <y3 <1) and a Ga _x2 In _1-x2 N _z2
An intermediate layer made of a group III-V semiconductor not containing Al and N is provided between an active layer made of P _{1 -z2} (0 ≦ x2 ≦ 1, 0 <z2 <1). As described above, a structure in which the clad layer or the guide layer containing Al and the GaInNP active layer containing N are separated from each other by the intermediate layer made of a III-V semiconductor containing no Al and N, thereby achieving good crystallinity. A GaInNP active layer can be obtained, and an element having high luminous efficiency can be obtained.

Here, the intermediate layer made of a III-V semiconductor containing no Al and N is a monoatomic layer or more,
It is preferable that the thickness be sufficiently smaller than the thickness of the nNP active layer.

That is, in the conduction band and valence band of the heterojunction composed of the intermediate layer made of a III-V semiconductor not containing Al and N and the active layer, the potential energy of the intermediate layer as viewed from the carrier is higher than that of the active layer. High (type I junction) and the width of the intermediate layer (thickness of the intermediate layer) is about the same as the width of the active layer (the width of the quantum well; the thickness of the active layer), the substantial carrier confinement is This is performed by a structure in which the layer is a barrier. In this case, the emission wavelength is determined by the band discontinuity of the intermediate layer, and becomes longer by inserting an intermediate layer having a thickness approximately equal to the active layer width (quantum well width; active layer thickness).

In the conduction band and valence band of the heterojunction consisting of the intermediate layer made of a III-V semiconductor not containing Al and N and the active layer, the potential energy of the intermediate layer viewed from the carrier is higher than that of the active layer. (Type II
When the thickness of the intermediate layer is substantially the same as the thickness of the active layer, a quantum level is formed in the intermediate layer having a low potential energy, and the emission wavelength becomes a long wavelength.
In addition, the probability amplitude of carriers in the intermediate layer, which is determined by quantum mechanics, is increased by this. When the heterojunction composed of the intermediate layer and the active layer forms Type II,
The overlap integral value of the carrier probability amplitude between the two bands decreases, and the luminous efficiency decreases.

As described above, in order to realize a light emitting device having a high characteristic temperature at a short wavelength of, for example, 600 nm or less, which is an object of the present invention, the type of the intermediate layer is more preferable, and the thickness of the intermediate layer is more preferable. The thickness is at least a monoatomic layer and is at least sufficiently thin compared to the quantum well width (the thickness of the active layer).
(The wave function of the carrier is so thin as not to be significantly modulated by the potential of the intermediate layer). Type II may be used as long as the influence on the wave function is small. Thus, regardless of the joining type,
It must be thin enough. Such a type,
By using an intermediate layer having a thickness, the AlGaInP guide layer (or cladding layer) and the GaInNP active layer
Suitable III-V semiconductor layer (intermediate layer) not containing Al and N
It is possible to realize an element having a high characteristic temperature when separating by.

The intermediate layer is preferably made of a III-V semiconductor of three or less constituent elements not containing Al and N.

That is, N and P were contained as group V elements.
In the group III-V mixed crystal semiconductor light emitting device, the mixed crystal semiconductor has a higher degree of immiscibility as the number of constituent elements is larger, and it is difficult to obtain a high quality crystal. As described above, it is difficult to grow a GaInNP active layer on an AlGaInP clad layer or guide layer (barrier layer).
In addition to the presence of l, the fact that there are many types of constituent elements at the start of growth is considered to have an effect. The same can be said for the case where an active layer is grown on the intermediate layer. Therefore, it is desirable that the intermediate layer also has a small number of constituent elements. Therefore, in the present invention, a GaInNP active layer having good crystallinity and an upper layer are formed using an intermediate layer of three or less types of constituent elements not containing Al and N. Thereby, the AlGaInP guide layer or the clad layer and the GaI
The nNP active layer is made of a suitable III-V containing no Al and N.
When separated by a group III semiconductor layer (intermediate layer), an element having a high characteristic temperature can be realized.

More specifically, the intermediate layer is made of, for example, a III-V semiconductor composed of two constituent elements not containing Al and N. That is, the III-V semiconductor of the two constituent elements is
It can be grown most easily and with good crystallinity. Therefore, in the present invention, by using a III-V group semiconductor of two kinds of constituent elements not containing Al and N as the intermediate layer, Ga with good crystallinity is obtained.
It becomes possible to obtain an InNP active layer and an upper layer.

Alternatively, when a GaAs substrate is used as the semiconductor substrate, Ga _x4 In _1-x4 P
A mixed crystal semiconductor (0 <x4 <1) can also be used. By using GaInP for the intermediate layer, an intermediate layer having the same lattice constant as the cladding layer or the guide layer can be formed.
Control of the strain amount of the P active layer can be made relatively easy. Further, since the mixed crystal species of the GaInNP active layer and the AlGaInP cladding layer are similar, it is possible to grow a high-quality crystal relatively easily. At this time, as described above, the intermediate layer needs to be a monoatomic layer or more, and have a thickness sufficiently smaller than the thickness of the GaInNP active layer.

Alternatively, when GaAs is used as the semiconductor substrate, GaP having a thickness equal to or less than the critical thickness at which misfit transition occurs can be used as the intermediate layer. G
aP has the largest bandgap energy among III-V semiconductors containing no Al and N, and can reduce loss due to light emission in the intermediate layer. Further, the intermediate layer is made of A
Since a binary III-V semiconductor containing neither l nor N is used, it is possible to obtain an intermediate layer, a GaInNP active layer, and an upper layer film having good crystallinity. More specifically, the thickness of the intermediate layer used at this time is not more than the critical film thickness at which misfit dislocation occurs, and is not less than a monoatomic layer, and at least the quantum well width (the thickness of the active layer). Must be sufficiently thin (so that the wave function of carriers is not significantly modulated by the potential of the intermediate layer).

Alternatively, when GaP is used as the semiconductor substrate, a Ga _x5 In _1-x5 P mixed crystal semiconductor (0 <x5 <1) can be used as the intermediate layer. GaInP
As described above, the larger the Ga composition, the larger the band gap energy and the smaller the lattice constant.
Since the lattice constant is further reduced by the addition of nitrogen, if GaP having a smaller lattice constant than GaAs is selected for the substrate, GaI having a composition with a large band gap energy is used.
Since nNP can be formed with a smaller amount of strain than on a GaAs substrate, it is easier to shorten the wavelength. In addition, since the intermediate layer is made of GaInNP, an active layer having good crystallinity and an upper layer film can be obtained.

In another embodiment of the semiconductor light emitting device of the present invention, a III-V semiconductor intermediate layer is formed at each boundary between a cladding layer or a guide layer (barrier layer) and a GaInNP active layer. Or a guide layer and GaInN
A multi-quantum well structure having a light emitting portion is formed by a laminated structure in which a III-V group semiconductor intermediate layer is formed at each boundary with the P active layer. That is, in this embodiment,
The light emitting section has a multiple quantum well structure, and an intermediate layer having any one of the above-described configurations is provided at each boundary between the active layer and the cladding layer or the guide layer. In such a configuration,
When increasing the amount of light emission by the multiple quantum well structure, an active layer and an upper layer film having good crystallinity can be obtained.

Heretofore, a quantum well structure using an active layer as a thin film has been generally used for shortening the wavelength of a semiconductor light emitting device. AlGaInP-based materials include AlGaInP
The guide layer (or cladding layer) is used as a barrier layer, and GaInP
Carriers are confined in the well layer. That is, in this case, since AlGaInP contains Al in its composition, it becomes a wide gap and functions as a barrier layer.
However, when GaInNP is used as the active layer, it is necessary to insert an intermediate layer not containing Al and N in the composition between the active layer and the guide layer or the clad layer, as described above.
In such a composition of the intermediate layer, the band gap energy is smaller than that of the guide layer or the cladding layer, and therefore, Ga
There is a limit to effectively functioning as a quantum confinement barrier layer for the InNP active layer.

Therefore, it is necessary to perform quantum confinement of carriers by using a structure in which the intermediate layer and the active layer are effective well layers and the AlGaInP clad layer or the guide layer is a barrier layer. However, as described above, the intermediate layer must completely cover the lower layer, and must have a thickness of at least one atomic layer. Furthermore, in consideration of crystal growth conditions, surface flatness, and controllability of the interface, a thickness larger than that is usually required except for specially selected growth conditions. Further, in order to sufficiently obtain the effects of the present invention, Ga
The thickness of the InNP active layer needs to be larger than the thickness of the intermediate layer. However, when a thick intermediate layer is required as described above, there is a limit to reducing the effective well width while keeping the GaInNP active layer at a sufficient thickness.
Therefore, it is difficult to sufficiently shorten the wavelength by the quantum effect.

On the other hand, the inventor of the present application has found that the improvement of the crystallinity by the intermediate layer largely depends on the intermediate layer located on the substrate side. That is, AlGaIn
When GaInNP is grown on P, the degree of crystallinity is more greatly reduced, and the crystallinity of the active layer and the laminated structure is substantially determined by this process during growth. Therefore, particularly when it is important to reduce the effective well width, it is sufficiently possible to arrange the intermediate layer only on the substrate side with respect to the active layer.

However, when the intermediate layer is disposed only on the substrate side, the symmetry of the potential of the active layer portion including the intermediate layer is broken, and the symmetry between the carrier wave functions is lost. As a result, the overlap integral intensity of the wave functions is reduced, which has an effect such as a decrease in luminous efficiency. Therefore, in the case where the active layer is thick, it is desirable to have a symmetrical structure in which an intermediate layer is disposed on both sides of the active layer. Since the well width is thin and the quantum level is sufficiently high, the asymmetry of the carrier wave function due to the potential is small. Therefore, the influence on the luminous efficiency is small, so that the intermediate layer can be disposed only on the substrate side.

As described above, when the intermediate layer is arranged only on the substrate side, the effective well width can be reduced, and the wavelength can be shortened by the quantum well structure. Also, when compared with the same effective well width, the proportion of the GaInNP active layer is also increased, so that the effect of shortening the wavelength and simultaneously improving the characteristic temperature by the GaInNP active layer can be sufficiently obtained. As described above, an element having a high characteristic temperature in which N is added to the active layer can be realized.

As a specific example of the structure of the semiconductor light emitting device, the light emitting portion has a multiple quantum well structure,
a barrier layer on the substrate side with respect to the nNP active layer;
A III-V semiconductor intermediate layer can be formed at each boundary with the nNP active layer. In this case, when the light emission amount is increased by the multiple quantum well structure, an active layer and an upper layer film having good crystallinity can be obtained. This makes it possible to easily shorten the wavelength and to realize an element having a high characteristic temperature in which N is added to the active layer.

[0052]

Embodiments of the present invention will be described below.

[0053]Example 1  In the first embodiment, N (nitrogen) is used as a group V element on a semiconductor substrate.
III-V mixed crystal semiconductor layer containing P and phosphorus as an active layer
As a semiconductor light emitting device used for_x2In
_1-x2N_z2P_1-z2(0 ≦ x2 ≦ 1, 0 <z2 <1)
(Sample) was prepared. FIG. 1 and FIG.
AlG grown by MOCVD on s substrate
In the micrograph of the surface of the sample of aInNP and GaInNP
is there. Here, each of AlGaInNP and GaInNP
Is 1 μm. The substrate has a 100-plane orientation.
Have a plane orientation inclined by 15 ° in the 011 direction
Was used. The carrier gas is H_TwoUsing raw material gas
TMG, TMA, TMI, PH_ThreeWas used. Ma
DMHy was used as a nitrogen-added raw material. AlGaIn
Both NP and GaInNP samples are lattice matched to the substrate
Nitrogen was added to the conditions. The composition is A
l_0.1Ga_0.5In_0.5N_z2P_1-z2(0 <z2 <1), Ga
_0.5In_0.5N_z1P_1-z1(0 <z1 <1).

As can be seen by comparing FIG. 1 and FIG.
In the case of lGaInP crystal, roughness occurs on the surface.
The surface of the nNP crystal is a mirror surface. Group N element contains N
It is already known that III-V group semiconductors tend to have lower crystallinity as the amount of incorporated nitrogen increases. Also, the higher the growth temperature, the more difficult it is to take in nitrogen. The growth of GaInNP depends on the group V flow rate (DM
Hy / PH ₃ ) is about 17 times higher than AlGaInNP, and the temperature is lower than that of AlGaInNP. From this, it can be said that the amount of nitrogen taken in is higher in the GaInNP crystal than in the growth condition in which surface roughness is likely to occur. Despite this, GaInNP did not cause surface roughness. In addition, the room temperature PL measurement results in a longer wavelength of 30 nm as compared with the case where nitrogen is not added,
That is, it was confirmed that the band gap energy was reduced. The N concentration was 1.1 × 10 ²⁰ cm ⁻³ (nitrogen group V composition ratio: 0.5%).

AlGaInP originally has problems such as low luminous efficiency due to the deep level of Al.
In addition, the crystallinity is significantly reduced by the addition of nitrogen, and it is difficult to obtain high-quality crystals. On the other hand, GaInP
It was confirmed that, since Al did not contain Al, the luminous efficiency was good, and even when nitrogen was added, good crystals could be grown. In addition, it was actually observed that the wavelength was increased by adding nitrogen. Further, GaInP is different from AlGaIn in that the number of constituent elements is smaller than that of AlGaInNP.
It has the advantage that high quality crystal growth is easier than NP.

As described above, according to the first embodiment of the present invention, Ga
It can be seen that by using InNP as an active layer of a light-emitting element, an element having good crystallinity and high characteristic temperature can be realized.

Example 2 In Example 2, the semiconductor laminated structure shown in FIG. 3 was manufactured. That is, the semiconductor multilayer structure shown in FIG. 3 was formed on the GaAs substrate 11 by epitaxially growing an SQW (Single Quantum Well) structure by MOCVD. The configuration of each layer is, in order from the substrate 11 side, an undoped GaAs buffer layer (0.2 μm thick) and an undoped AlGaInP barrier layer (0.2 μm thick (Al _0.5 Ga _0.5 ) _0.49 In
_0.51 P clad layer) 13, undoped GaInP intermediate layer
(Ga _0.65 In _0.35 P intermediate layer having a thickness of 12Å) 14, Ga _0.65 undoped GaInNP active layer (350 Å in thickness
In _0.35 N _0.008 P _0.992 active layer) 15, undoped Ga
InP intermediate layer (Ga _0.65 In _0.35 P intermediate layer having a thickness of 12 °) 16, undoped AlGaInP barrier layer (500 °
(Al _0.5 Ga _0.5 ) _0.49 In _0.51 P cladding layer
Seventeen.

Here, the thickness of the GaInP intermediate layers 14 and 16 is about 4 atomic layers, which is sufficiently thinner than the active layer 15. Also, as the substrate 11,
A GaAs substrate having a plane orientation inclined by 15 ° in the (011) direction with respect to the (100) plane orientation was used. The raw materials include TM
G, TMI, TMA, PH ₃ and AsH ₃ are used, DMHy is used as a nitrogen-added raw material, and H is used as a carrier gas.
₂ was used.

For the barrier layers (cladding layers) 13 and 17, AlGaInP (specifically, (Al _0.5 Ga _0.5 ) _0.49 In _0.51 P) having a composition lattice-matched to the substrate 11 was used. Also, the intermediate layers 14 and 16 have a 1%
GaInP having a composition that results in a tensile strain of
Ga _0.65 In _0.35 P) is used, and the GaInNP active layer 15 is obtained by adding nitrogen to the composition conditions of the intermediate layers 14 and 16 (specifically, Ga _0.65 In _0.35 N _0.008 P _0.992 ).
Was used. Further, the amount of nitrogen (N) taken into the GaInNP active layer 15 depends on the Ga / In composition ratio, and the larger the Ga composition, the larger the amount of nitrogen (N) taken. This condition is a condition under which nitrogen is easily taken in. The composition of the active layer 15 is Ga _0.65 In as described above.
_0.35 N _0.008 P _0.992 .

As described above, GaInP having a large Ga composition
When nitrogen is added, the efficiency of taking in nitrogen is increased and the effect of lowering the energy of the conduction band is sufficiently obtained. Furthermore, GaInNP having a high band gap energy can be obtained, which is advantageous in shortening the wavelength.

FIGS. 4 (a), 4 (b) and 4 (c) show the same growth conditions as those of the second embodiment (FIG. 3) (FIG. 4 (a)) and the second embodiment, respectively. Structure with no intermediate layer inserted
(FIG. 4B), a structure having a GaInP active layer without nitrogen addition instead of the active layer 15 of the structure of the second embodiment.
The PL (light intensity) measurement result at room temperature in FIG. 4 (c) is shown. In the structure of Example 2 (FIG. 3), as can be seen from FIG. 4A, the wavelength becomes longer due to the addition of nitrogen to the active layer. On the other hand, in the structure in which the intermediate layer is not provided, as can be seen from FIG. Further, in the structure having the GaInP active layer to which no nitrogen is added, as can be seen from FIG. 4C, the peak emission wavelength is 626 nm. On the other hand, in the structure of Example 2, as can be seen from FIG. 4A, the peak emission wavelength becomes 665 nm by addition of nitrogen, and the peak emission wavelength in FIG. The wavelength has changed. That is, the effect of adding nitrogen is sufficiently obtained.

As described above, when no intermediate layer was used, light emission was not confirmed and practical use was difficult. However, according to the structure of the second embodiment, as shown in FIG. The luminous efficiency can be improved. This makes it possible to realize an element having a high characteristic temperature. Also,
As described above, the wavelength can be shortened by the quantum well structure and by using the one having a larger Ga composition.

The GaInP intermediate layer 1 of the second embodiment
4, 16 and the GaInNP active layer 15 are known LEDs,
As described later, for example, in Example 3,
It can be used as a light emitting layer of an element having a structure of 4,5.

Example 3 In Example 3, the semiconductor laminated structure shown in FIG. 5 was manufactured. FIG.
In the semiconductor laminated structure (semiconductor light-emitting element), n-GaAs
On a substrate 501, an n-buffer layer 502, an n-cladding layer 503, an intermediate layer 510, an active layer 504, an intermediate layer 51
1, a p-cladding layer 505 and a p-contact layer 506 are sequentially formed.

Here, for the active layer 504, GaInNP obtained by adding nitrogen to GaInP having a composition lattice-matched to the GaAs substrate 501 is used. Also, the intermediate layers 510, 5
No. 11 uses GaP having a thickness equal to or less than the critical film thickness at which misfit dislocations occur and a thickness of two molecular layers.

More specifically, the structure of FIG.
An s-substrate 501 whose plane orientation is inclined by 15 ° from the (100) plane toward the (011) direction is used.
n-GaAs buffer layer 502, n- (Al _0.7 Ga _0.3 )
_0.51 1In _0.49 clad layer 503, GaP intermediate layer 51
0, Ga _0.51 In _0.49 N _0.01 P _0.99 Active layer 504, Ga
P-intermediate layer 511, p- (Al _0.7 Ga _0.3 ) _0.51 1In
_0.49 cladding layer 505, p-GaAs contact layer 50
6 are sequentially formed from the raw material of Example 2 by MOCVD, for example. Here, the cladding layers 503 and 505 have a composition lattice-matched to the GaAs substrate 501.

In the semiconductor light emitting device of FIG. 5, the insulating film 507 of SiO ₂ is further formed on the contact layer 506.
And AuZn / Au as the p-side electrode 508 are formed, and AuG as the n-side electrode 509 is formed on the back surface of the element.
e / Ni / Au is formed.

The semiconductor light emitting device shown in FIG.
3,505 and the active layer 504 function as a semiconductor laser device having a double hetero junction structure. In the third embodiment, GaInP lattice-matched to the GaAs substrate 501 is obtained by adding nitrogen as the active layer 504. However, since the lattice constant is reduced by the addition of nitrogen, this is compensated for in advance and the Ga composition is reduced. Large (large lattice constant)
If Ga _0.49 In _0.51 N _0.01 P _0.99 is used as the active layer 504, lattice matching with the substrate 501 is possible.

In the third embodiment (the structure shown in FIG. 5), the light emitting element has an insulating film stripe structure. However, other structures may be used. Further, as in the second embodiment, an active layer having a strain equal to or less than a critical film thickness at which misfit dislocation occurs may be used as the active layer 504. In this case, the obtained emission wavelength width increases,
The degree of freedom in element design can be increased. Alternatively, the active layer 504 may have a shorter wavelength by using a quantum well structure.

In the above-described example, GaP is used as the intermediate layers 510 and 511 having two constituent elements.
Instead of P, GaAs, InP or the like may be used. For example, when GaAs is used for the intermediate layers 510 and 511, the intermediate layers 510 and 511 have the same lattice constant as the substrate 501.
There is an advantage that can be formed. Also, the middle layer 510,
When InP is used for 511, the intermediate layers 510, 51
It is necessary that the thickness of No. 1 be equal to or less than the critical thickness at which misfit dislocation occurs. Other intermediate layers 510 and 511 include
Although a group III-V semiconductor may be used, it is preferable that the semiconductor has a wide gap as much as possible (it is desirable that the band gap energy is large) in consideration of light emission efficiency and light emission wavelength. GaP has a large band gap energy, and if GaP having a large band gap energy is used for the intermediate layers 510 and 511, a GaInNP active layer and an upper layer film with low luminescence loss in the intermediate layers 510 and 511 and excellent crystallinity can be obtained. It becomes possible. Thereby, an element having a high characteristic temperature can be realized.

Example 4 In Example 4, a semiconductor laminated structure shown in FIG. 6 was manufactured. FIG.
Is formed on an n-GaP substrate 601 by forming an n-buffer layer 602, an n-cladding layer 6
03, n-guide layer 612, intermediate layer 610, active layer 60
4, an intermediate layer 611, a p-guide layer 613, a p-cladding layer 605, and a p-contact layer 606 are sequentially formed.

Here, the active layer 604 includes Ga _0.7 In
GaInNP obtained by adding nitrogen to _0.3 P is used. Similarly, Ga _0.7 In _0.3 P is used for the intermediate layers 610 and 611. Further, the semiconductor substrate 601 is significantly different from the third embodiment in that GaP is used.

More specifically, the structure of FIG.
On a substrate 601, an n-GaP buffer layer 602, n-A
1P clad layer 603, n-Al _0.5 Ga _0.5 P guide layer 612, Ga _0.7 In _0.3 P intermediate layer 610, Ga _0.7 In
_0.3 N _0.01 P _0.99 active layer 604, Ga _0.7 In _0.3 P intermediate layer 611, n-Al _0.5 Ga _0.5 P guide layer 613, p-
AlP cladding layer 605, p-GaP contact layer 60
6 has a structure in which the raw materials of Example 2 are sequentially formed by MOCVD, for example.

In the semiconductor light emitting device of FIG. 6, on the contact layer 606, an insulating film 607 of SiO
₂ and a p-side electrode 608 are formed, and an n-side electrode 609 is formed on the back surface of the element. Here, the semiconductor light emitting device includes guide layers 612 and 613 and an active layer 60.
4 functions as a semiconductor laser device having a double heterojunction structure.

In the structure of FIG. 6, the active layer 604 is a direct transition type GaInP having a composition with the largest band gap (composition with the smallest lattice constant) and nitrogen added thereto. The guide layers 612 and 613 are formed on the GaP substrate 6.
01 is almost lattice-matched.

In the above example, the intermediate layers 610 and 61
For example, Ga _0.7 In _0.3 P having a thickness of 4 atomic layers was used,
Alternatively, a GaP intermediate layer can be used.
In this case, the GaP intermediate layers 610 and 611 can be formed in lattice matching with the substrate 601.

FIG. 7 shows the AlP cladding layers 603 and 605 and the AlGaP guide layers 612 and 6 of the semiconductor light emitting device of FIG.
13, GaInP intermediate layers 610 and 611 and GaInNP
FIG. 3 is a diagram for explaining a band structure of an active layer 604.
In the light emitting device of FIG. 6, since the refractive index of AlP forming the cladding layers 603 and 605 is smaller than the refractive index of Al _0.5 Ga _0.5 P forming the guide layers 612 and 613, light can be confined well. it can. In addition, this makes it possible to reduce the threshold current value. In addition,
The composition is such that the light guide layers 612 and 613 are Al _y1 Ga _1-y1 P
(0 ≦ y1 <1), and the cladding layers 603 and 605
If l _y2 Ga _1-y2 P (0 ≦ y1 <y2 ≦ 1), the composition is not limited to the above-mentioned composition, but may be another composition.

In the structure of the fourth embodiment (FIG. 6), GaP is Ga
The lattice constant is smaller than that of As, and the lattice constant of GaInP is smaller as the Ga composition is larger. Furthermore, addition of nitrogen reduces the lattice constant, so using a GaP substrate can reduce the active layer with a large bandgap energy and reduce the strain.
(Compression strain) amount, which is advantageous in shortening the wavelength. That is, according to the structure of the fourth embodiment, it is possible to obtain an active layer which is advantageous for shortening the wavelength and has good crystallinity, and an upper film. This makes it possible to realize an element having a high characteristic temperature.

Example 5 In Example 5, the semiconductor multilayer structure shown in FIG. 8 was manufactured. In the semiconductor laminated structure (semiconductor light emitting device) of the fifth embodiment (FIG. 8), n
An n-buffer layer 702, n on a GaAs substrate 701;
A cladding layer 703, an n-guide layer 712, a multiple quantum well structure (MQW), a p-guide layer 713, a p-cladding layer 705, and a p-contact layer 706 are sequentially formed.

More specifically, the structure of FIG.
On an s substrate 701, an n-GaAs buffer layer 702, n
− (Al _x1 Ga _1-x1 ) _0.51 In _0.49 P cladding layer (0 <x
1 ≦ 1) 703, n- (Al _x2 Ga _1-x2 ) _0.51 In _0.49 P
Guide layer (0 <x2 <x1 ≦ 1) 712, multiple quantum well structure (MQW), p- (Al _x2 Ga _1-x2 ) _0.51 In _0.49 guide layer 713, p- (Al _x1 Ga _1-x1 ) _0.51 The In _0.49 P cladding layer 705 and the p-GaAs contact layer 706 are formed sequentially by the MOCVD method using the raw material of the second embodiment.

The multiple quantum well (MQW) has the same composition as the guide layers 712 and 713 (Al _x2 Ga ₁ -x ₂ ) _0.51 In
_0.49 P barrier layer 714 and Ga _0.51 In _0.49 N _0.01 P _0.99
The structure is such that a Ga _0.51 In _0.49 P intermediate layer 710 (or 711 or 715) is inserted at each boundary with the active layer 704.

In the semiconductor light emitting device of FIG. 8, on the contact layer 706, an insulating film 707 of SiO
₂ and a p-side electrode 708 are formed, and an n-side electrode 709 is formed on the back surface of the element. Here, this semiconductor light emitting device functions as a semiconductor laser device having a multiple quantum well in an active layer.

In the structure shown in FIG. 8, when increasing the amount of light emission by the multiple quantum well structure, an element having good crystallinity of the active layer and the upper layer can be obtained by the intermediate layers 710 and 711. This makes it possible to realize an element having a high characteristic temperature with a multiple quantum well structure.

Example 6 In Example 6, the (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P layer was used as a barrier layer, and Ga _0.5 In _0.5 N _z P ₁ -z was used without using an intermediate layer.
An active layer was grown. FIG. 9 shows (Al _0.5 Ga _0.5 ) _0.5 In
_0.5 P layer as a barrier layer, Ga _0.5 I
n _0.5 N _z P _1-z active layer of the sample grown SIMS analysis result is a diagram showing a. The depth direction of FIG.
It is on the substrate side. The nitrogen (N) concentration in AlGaInP is at the background level, and nitrogen is contained in the GaInNP layer. From FIG. 9, AlGaIn on the substrate side
It can be seen that the nitrogen element (N) is segregated at the P / GaInNP interface. This is due to the fact that the uptake of nitrogen is increased due to the contact between the chemically active Al element and the N element. Due to the segregation of nitrogen (N), the growth surface is rough. Under similar growth conditions, GaInN
When the Ga _0.5 In _0.5 P intermediate layer is inserted on both sides of the P layer, no segregation of nitrogen element is observed, and a mirror surface is obtained on the growth surface.
Crystallinity can be greatly improved. This is because the Al element and the nitrogen element are separated by the intermediate layer.

Further, as shown in FIG. 9, the segregation of nitrogen at the interface is particularly remarkable on the substrate side. Even when the intermediate layer is inserted only on the substrate side, a mirror surface can be obtained on the growth surface, and a sufficient effect can be obtained. can get.

FIG. 10 shows that the GaInP intermediate layer is made of GaInN.
FIG. 1 is a band diagram in the case of being disposed on both sides of a P active layer, and FIG.
1 is a band diagram in the case where the GaInP intermediate layer is arranged only on the substrate side with respect to the GaInNP active layer. Thus, by arranging the intermediate layer only on the substrate side, the effective well thickness can be reduced with the same intermediate layer thickness ds and GaInNP active layer thickness da (d1 <d0). Accordingly, when compared with the same GaInNP active layer thickness da, the electron level is higher in FIG. 11 (Ee ′> Ee) and the hole level is lower in FIG. 11 (Eh ′ <Eh). Also, relatively Ga
Since the proportion occupied by the InNP layer also increases (that is, (d
a / d1)> (da / d0)), it is possible to shorten the wavelength while maintaining the effect of effectively increasing the discontinuity of the conduction band due to the addition of nitrogen.

Example 7 In Example 7, the semiconductor laminated structure shown in FIG. 12 was manufactured. In the seventh embodiment (semiconductor multilayer structure in FIG. 12), an n-GaAs buffer layer 802 and an n-
(Al _x1 Ga _1-x1 ) _0.51 In _0.49 P cladding layer (0 <x1
≦ 1) 803, undoped (Al _x2 Ga _1-x2 ) _0.51 N _0.49
P guide layer (0 <x2 <x1 ≦ 1) 812, multiple quantum well structure (MQW), undoped (Al _x2 Ga _1-x2 ) _0.51 N
_0.49 P guide layer 813, p- (Al _x1 Ga _1-x1 ) _0.51 In
_0.49 P cladding layer 805, p-GaAs contact layer 8
No. 06 is sequentially formed from the raw material of Example 2 by MOCVD, for example.

Here, the multiple quantum well (MQW) has the same composition as the guide layers 812 and 813 (Al _x2 Ga _{1 -x 2} ) _0.51 I
n _0.49 P barrier layer 814 and Ga _0.51 In _0.49 N _0.01 P
_0.99 active layer 804 and Ga _0.51 In _0.49 P intermediate layer 810
(Or 815), and the intermediate layer 810 (or 815) is inserted at the boundary between the active layer on the substrate side with respect to the active layer 804 and the barrier layer (or guide layer).

In the semiconductor light emitting device (semiconductor laser device) shown in FIG. 12, SiO _{2 serving as} an insulating film 807 and a p-side electrode 808 are further formed on the contact layer 806. An n-side electrode 809 is formed. Here, this semiconductor light emitting device functions as a semiconductor laser device having a multiple quantum well in an active layer. This makes it possible to realize an element having a high characteristic temperature in which N is added to the active layer and capable of easily shortening the wavelength with a multiple quantum well structure.

[0090]

As described above, according to the first to ninth aspects of the present invention, a III-V group containing N (nitrogen) and P (phosphorus) as group V elements on a semiconductor substrate. a semiconductor light emitting device using the mixed crystal semiconductor layer as an active layer, the active layer is _{Ga x2 in 1-x2 N z2} P 1-z2 (0 ≦ x2 ≦ 1,0 <z2
Since <1), light emission in the visible wavelength region can be obtained. Further, by adding N to GaInP as an active layer, the band gap energy becomes smaller and the energy in the conduction band and the valence band becomes lower than in the case where N is not added. Therefore, by selecting the composition, it is possible to form a heterojunction having an unconventional and arbitrary band offset ratio having a large conduction band discontinuity. That is, it is possible to realize an element having a high characteristic temperature that operates stably even at a high temperature compared to the related art.

By the way, most of such mixed crystal semiconductors containing N in the group V element are in an immiscible region, and crystal growth is very difficult. MOCVD method with high non-equilibrium degree
(Metalorganic vapor phase epitaxy) or MBE (Molecular beam epitaxy) can grow crystals with a slight nitrogen composition. As the number of constituent elements increases, the mixed crystal semiconductor becomes more immiscible. Even with the same mixed crystal, a mixed crystal having an intermediate composition has higher immiscibility. That is, in the mixed crystal semiconductor, the binary compound is most likely to grow. The same can be said for a mixed crystal semiconductor containing N in a group V element. Since AlGaInNP is a quinary mixed crystal, it is difficult to obtain a high-quality crystal. The fact that Al is chemically active and easily grows three-dimensionally also makes this difficult.

In the present invention, a high-quality crystal can be easily obtained and the luminous efficiency can be improved by using GaInNP having a smaller number of constituent elements and containing no Al for the active layer. At this time, it is advantageous to select an active layer having a high Ga composition. Nitrogen is
This is because GaInP having a larger Ga composition can be added more. Thereby, the effect of sufficiently lowering the energy of the conduction band can be obtained. Further, addition of nitrogen reduces the band gap energy of the mixed crystal, and therefore, it is important to use a composition having a large Ga composition (large band gap energy) even in shortening the wavelength. By selecting an appropriate composition in this way, a light-emitting element having a high characteristic temperature even at a short wavelength emission wavelength can be obtained.

As described above, by adding nitrogen to GaInP containing no Al, an active layer having good crystallinity can be obtained. However, in a device in which a GaInNP active layer is directly formed on an AlGaInP guide layer (or a cladding layer), it is difficult to sufficiently increase the luminous efficiency, although the crystallinity is greatly improved. This is GaInN
This is because at the start of the growth of the P active layer, Al atoms are included in the constituent elements on the growth surface, and the crystallinity at the heterojunction interface affects the crystallinity of the GaInNP active layer and the upper layer film of the GaInNP active layer. Is given.

This problem is solved by the method according to the second aspect of the present invention, in which (Al _x3 Ga _1-x3 ) _y3 In _1-y3 P (0 ≦ x3 ≦ 1,0
<Y3 <1) and a guide layer or a cladding layer made of Ga
between _{x2 In 1-x2 N z2 P} 1-z2 (0 ≦ x2 ≦ 1,0 <z2 <1) composed of the active layer, having an intermediate layer made of a group III-V semiconductor containing no Al and N That can be improved. That is, the AlGaInP guide layer (or cladding layer) and G
aInNP active layer and a suitable Al- and N-free III
The above problem can be improved by separating at the -V group semiconductor layer (intermediate layer).

In other words, the cladding layer containing Al and N
Is separated from the GaInNP active layer containing by an intermediate layer, it is possible to obtain a GaInNP active layer having good crystallinity. This makes it possible to obtain an element having a high characteristic temperature.

Further, according to the third aspect of the present invention,
The intermediate layer made of a III-V semiconductor not containing N and N is preferably a monoatomic layer or more and sufficiently thinner than the thickness of the GaInNP active layer. Thereby, 600n
It is possible to realize a light emitting device having a high characteristic temperature at a short wavelength of less than m.

Further, as in the fourth aspect of the present invention, the intermediate layer is composed of three or less constituent elements III-
It is preferable to be made of a group V semiconductor. By using an intermediate layer of three or less types of constituent elements not containing Al and N, it is possible to form a GAInNP active layer and an upper layer with good crystallinity, thereby realizing an element having a high characteristic temperature. It becomes possible.

Further, according to the invention as set forth in claim 5, Al
And III-V semiconductors, which are two types of constituent elements not containing N, are used as the intermediate layer, so that GaIn having higher crystallinity can be obtained.
An NP active layer and an upper layer can be obtained. This makes it possible to realize an element having a high characteristic temperature.

In the case where a GaAs substrate is used as the semiconductor substrate, a Ga _x4 In _1-x4 P mixed crystal semiconductor (0 <x4 <1) is used as the intermediate layer. An intermediate layer having the same lattice constant as the cladding layer or the guide layer can be formed, and control of the amount of strain of the GaInNP active layer can be relatively easily performed. GaIn
Since the mixed crystal species of the NP active layer and the AlGaInP cladding layer are similar, it is possible to grow a high-quality crystal relatively easily. In this case, the intermediate layer needs to have the thickness described in claim 3. This makes it possible to realize an element having a high characteristic temperature.

In the case where GaAs is used as the semiconductor substrate, GaP having a thickness equal to or less than the critical thickness at which misfit transition occurs can be used as the intermediate layer. GaP does not contain Al and N III-
Since the bandgap energy is the largest among the group V semiconductors, loss due to light emission in the intermediate layer can be reduced. The intermediate layer is formed of a binary III-V containing no Al and N.
By using a group III semiconductor, an intermediate layer of good crystallinity, GaI
It is possible to obtain an nNP active layer and an upper layer film. More specifically, the thickness of the intermediate layer used at this time must be equal to or less than the critical film thickness at which misfit dislocations occur and satisfy the condition of claim 3. This makes it possible to realize an element having a high characteristic temperature.

Further, when GaP is used as the semiconductor substrate as in the invention of claim 8, G is used as the intermediate layer.
a _x5 In _1-x5 P mixed crystal semiconductor (0 <x5 <1) can be used. As for GaInP, the larger the Ga composition, the larger the band gap energy and the smaller the lattice constant, and the more the lattice constant becomes smaller by adding nitrogen. Therefore, if GaP having a smaller lattice constant than GaAs is selected for the substrate, G with large composition of band gap energy
aInNP can be formed on a GaP substrate with a smaller amount of distortion, and the wavelength can be easily shortened. Further, by using GaInNP for the intermediate layer, an active layer having good crystallinity and an upper layer film can be obtained as in the sixth aspect.
This makes it possible to realize an element having a high characteristic temperature.

According to the ninth aspect of the present invention, a III-V semiconductor intermediate layer is formed at each boundary between the cladding layer or guide layer and the GaInNP active layer, and the cladding layer or guide layer and the GaInNP active layer are formed. III-V for each boundary of
By forming a multiple quantum well structure having a light emitting part by a laminated structure of a structure in which a group III semiconductor intermediate layer is formed,
When the amount of light emission is increased by the multiple quantum well structure, an active layer with good crystallinity and an upper layer film can be obtained. This makes it possible to realize an element having a high characteristic temperature.

According to a tenth aspect of the present invention, in the semiconductor light emitting device according to any one of the second to sixth and eighth aspects, the intermediate layer is formed on a substrate with respect to an active layer. Since it is arranged only on the side, the effective well width can be reduced, and the wavelength can be shortened by the quantum well structure. Also, when compared with the same effective well width, GaIn
Since the proportion occupied by the NP active layer is also increasing, the effect of improving the characteristic temperature by the GaInNP active layer can be sufficiently obtained at the same time as shortening the wavelength. As described above, an element having a high characteristic temperature in which N is added to the active layer can be realized.

According to the eleventh aspect of the present invention, in the semiconductor light emitting device according to the tenth aspect, the GaInNP
Barrier layer and GaInNP on the substrate side with respect to the active layer
An intermediate layer is formed at each boundary with the active layer, and a barrier layer and Ga
Since it has a multiple quantum well structure having a light emitting portion formed by a laminated structure in which an intermediate layer is formed at each boundary with the InNP active layer, it is possible to easily shorten the wavelength,
In addition, an element having a high characteristic temperature in which N is added to the active layer can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a micrograph of the surface of an AlGaInNP sample grown on a GaAs substrate by MOCVD.

FIG. 2 is a diagram showing a microscope photograph of the surface of a GaInNP sample grown on a GaAs substrate by MOCVD.

FIG. 3 is a diagram illustrating a semiconductor multilayer structure according to a second embodiment of the present invention.

FIG. 4 shows the activity of the structure of Example 2 (FIG. 3), the structure in which the growth conditions are the same as those of Example 2, but no intermediate layer is inserted (FIG. 4B), and the structure of Example 2 FIG. 9 is a diagram showing the results of PL (light intensity) measurement at room temperature of a structure having a GaInP active layer without nitrogen addition instead of a layer.

FIG. 5 is a diagram illustrating a semiconductor multilayer structure according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating a semiconductor multilayer structure according to a fourth embodiment of the present invention.

FIG. 7 shows the AlP cladding layer and A of the semiconductor light emitting device of FIG.
FIG. 4 is a diagram for explaining a band structure of an lGaP guide layer, a GaInP intermediate layer, and a GaInNP active layer.

FIG. 8 is a diagram showing a semiconductor laminated structure according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing a SIMS analysis result of a sample in which a Ga _0.5 In _0.5 N _z P _{1 -z} active layer is grown without using an intermediate layer using an (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P layer as a barrier layer. It is.

FIG. 10 is a band diagram in a case where GaInP intermediate layers are arranged on both sides of a GaInNP active layer.

FIG. 11 is a band diagram in the case where a GaInP intermediate layer is disposed only on the substrate side with respect to the GaInNP active layer.

FIG. 12 is a diagram illustrating a semiconductor multilayer structure according to a seventh embodiment of the present invention.

[Explanation of symbols]

11 GaAs substrate 13 (Al _0.5 Ga _0.5 ) _0.49 In _0.51 P cladding layer 14 Ga _0.65 In _0.35 P intermediate layer 15 Ga _0.65 In _0.35 N _0.008 P _0.992 active layer 16 Ga _0.65 In _0.35 P intermediate layer 17 (Al _0.5 Ga _0.5 ) _0.49 In _0.51 P cladding layer 501 n-GaAs substrate 502 n-buffer layer 503 n-cladding layer 504 active layer 505 p-cladding layer 506 p-contact layer 507 insulating layer 508 p-side electrode 509 n-side electrode 510 intermediate layer 511 intermediate Layer 601 n-GaP substrate 602 n-buffer layer 603 n-cladding layer 604 active layer 605 p-cladding layer 606 p-contact layer 607 insulating layer 608 p-side electrode 609 n-side electrode 610 intermediate layer 611 intermediate layer 612 n-guide Layer 613 p-guide layer 701 n-GaAs substrate 702 n- Buffer layer 703 n-cladding layer 704 well layer 705 p-cladding layer 706 p-contact layer 707 insulating layer 708 p-side electrode 709 n-side electrode 710 intermediate layer 711 intermediate layer 712 n-guide layer 713 p-guide layer 714 barrier layer 715 intermediate layer 801 n-GaAs substrate 802 n-buffer layer 803 n-cladding layer 805 p-cladding layer 812,813 undoped guide layer 806 contact layer 804 active layer 814 barrier layer 810,815 intermediate layer 807 insulating film 808 p-side electrode 809 n-side electrode

Claims (11)

[Claims] 1. A semiconductor device comprising N (nitrogen) as a group V element on a semiconductor substrate.
A semiconductor light-emitting device using a group III-V mixed crystal semiconductor layer containing P and phosphorus as an active layer, wherein the active layer is Ga _x2
A semiconductor light emitting device, wherein In _1-x2 N _z2 P _1-z2 (0 ≦ x2 ≦ 1, 0 <z2 <1). 2. The semiconductor light emitting device according to claim 1, wherein said semiconductor light emitting device is (Al _x3 Ga _{1 -x3} ) _y3 In _{1 -y3.}
A guide layer or a cladding layer composed of P (0 ≦ x3 ≦ 1, 0 <y3 <1) and Ga _x2 In _1-x2 N _z2 P _1-z2 (0 ≦ x2 ≦
1, 0 <z2 <1) between the active layer and Al
A semiconductor light emitting device having an intermediate layer made of a group III-V semiconductor containing no. 3. The semiconductor light emitting device according to claim 2, wherein said intermediate layer is a monoatomic layer or more,
A semiconductor light emitting device characterized by being sufficiently thinner than the thickness of the P active layer. 4. The semiconductor light emitting device according to claim 2, wherein the intermediate layer does not contain Al and N.
A semiconductor light emitting device comprising a group III-V semiconductor of the following constituent elements. 5. The semiconductor light emitting device according to claim 4, wherein the intermediate layer is made of two kinds of constituent elements not containing Al and N.
A semiconductor light-emitting device comprising a III-V semiconductor. 6. The semiconductor light emitting device according to claim 3, wherein a GaAs substrate is used as said semiconductor substrate, and a Ga _x4 In _1-x4 P mixed crystal semiconductor (0 <x4 <1) as said intermediate layer. A semiconductor light emitting device characterized by using: 7. The semiconductor light emitting device according to claim 3, wherein the semiconductor substrate comprises Ga.
A semiconductor light emitting device, wherein As is used, and GaP having a thickness equal to or less than a critical thickness at which misfit transition occurs is used as the intermediate layer. 8. The semiconductor light emitting device according to claim 3, wherein GaP is used as the semiconductor substrate, and a Ga _x5 In _{1 -x5} P mixed crystal semiconductor (0) is used as the intermediate layer.
<X5 <1). A semiconductor light emitting device characterized by using <x5 <1). 9. The semiconductor light-emitting device according to claim 2, wherein the semiconductor light-emitting device has a III-V line at each boundary between the cladding layer or the guide layer and the GaInNP active layer. A multi-quantum well structure having a light emitting portion is formed by a stacked structure in which a group III semiconductor intermediate layer is formed, and a group III-V semiconductor intermediate layer is formed at each boundary between the cladding layer or the guide layer and the GaInNP active layer. A semiconductor light-emitting device. 10. The claim 2 to claim 6 and claim 8.
5. The semiconductor light emitting device according to claim 1, wherein the intermediate layer is disposed only on the substrate side with respect to the active layer. 11. The semiconductor light emitting device according to claim 10, wherein the intermediate layer is formed at each boundary between the barrier layer and the GaInNP active layer which are on the substrate side with respect to the GaInNP active layer. A semiconductor light-emitting device having a multiple quantum well structure having a light-emitting portion formed by a stacked structure in which an intermediate layer is formed at each boundary.