JPH1084131A - Semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting device having a good temperature characteristic, a long wavelength, and a structure easy to manufacture. SOLUTION: On a GaAs substrate 101 of a first conductivity type,
At least the active layer 1 made of a material having a smaller band gap energy and a larger refractive index than GaAs.
05, a first conductivity type lower cladding layer 103, a second conductivity type first upper cladding layer 107, and a second conductivity type second cladding layer 107.
It has an upper cladding layer 109 and a first conductivity type current blocking layer 108 for confining current. The current blocking layer 108 is made of a material having a smaller bandgap energy than GaAs. It also has a function as a layer that absorbs light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor light emitting device such as a semiconductor laser.

[0002]

2. Description of the Related Art Conventionally, an optical communication system using an optical fiber is mainly used in a trunk system, but is expected to be used in a subscriber system including each home in the future. To achieve this, it is necessary to reduce the size of the system, reduce power consumption, and reduce the cost. For this purpose, a semiconductor laser as a light source requires low threshold operation and Peltier-free operation. .

However, the current 1.3 μm wavelength band,
InGaAsP / 1.5 μm wavelength semiconductor lasers
InP-based materials are used, and semiconductor lasers using this material have a large threshold current mainly due to a small band discontinuity (ΔE _c ) in the conduction band and a large number of electron overflows. Further, there is a problem that the temperature characteristics are poor, and as a result, the light output greatly changes depending on the environmental temperature. For this reason, it is necessary to control the temperature, and this type of semiconductor laser uses a Peltier element for temperature control.

[0004] Such a problem is solved by InGaAsP / InP.
Since it is difficult to improve by using a system material, InGaAs is formed so as to increase the band discontinuity (ΔE _c ) of the conduction band.
Attempts have been made to form light-emitting elements using materials other than sP / InP-based materials. For example, InGaAs is formed on a GaAs substrate.
An attempt has been made to form a semiconductor laser using s.

However, InGa on a GaAs substrate
The band gap energy of As decreases as the In composition increases, but the lattice constant becomes larger than that of GaAs, and there is a problem that it is difficult to increase the wavelength to about 1.3 μm or 1.5 μm. That is, although a longer wavelength can be achieved by increasing the amount of compressive strain,
The limit was about 1 μm.

Therefore, in Japanese Patent Application Laid-Open No. 7-193327,
InGa giving a wavelength in the 1.3 μm or 1.5 μm band
An GaAs active layer and a GaAs
There has been proposed an element having a semiconductor layer having a lattice constant close to the lattice constant of s and having a large conduction band discontinuity (ΔE _c ).

That is, the device proposed in Japanese Patent Application Laid-Open No. 7-193327 uses an InGaAs active layer having a larger lattice constant than a GaAs substrate in order to provide a wavelength in the 1.3 μm or 1.5 μm band. InGa
Since As is used, a relaxation buffer layer is used to suppress generation of misfit dislocation due to a large lattice constant difference. However, even if a relaxation buffer layer is used, since it is basically a lattice mismatch system, there is a problem in the life of the device. In addition, the substrate is made of InG
Although it is conceivable to use aAs, the substrate may be made of InGaAs.
It is difficult to use multi-materials such as That is, it is actually difficult to manufacture a multi-material substrate such as InGaAs.

Therefore, Japanese Patent Application Laid-Open No. 6-37355 discloses that
It has been proposed to use an InGaNAs-based material on an aAs substrate, and to use InG as having a larger lattice constant than GaAs.
InGa reduced in lattice constant by adding N to aAs
By using an NAs-based material, the lattice constant can be made closer to the lattice constant of GaAs, lattice-matched with GaAs, and the band gap energy can be further reduced. That is, the InGaNAs-based material includes:
Since it is a material system capable of wavelengths in the 3 μm or 1.5 μm band and is a GaAs lattice matching system, the band discontinuity (ΔE _c ) of the conduction band can be increased by using AlGaAs for the cladding layer.

Further, Japanese Patent Application Laid-Open No.
As a semiconductor laser of an InGaNAs-based material on an aAs substrate, an SB having a ridge stripe portion (current block layer 6) embedded by selective growth by MOCVD as shown in FIG.
An element having an R (Selectively Buried Ridge Waveguide) structure is shown. In FIG. 3, 1 is a semiconductor laser element,
2 is a compound semiconductor substrate, 3 is an active layer, 4 is a lower cladding layer, 5 is an upper cladding layer, 6 is a current blocking layer, 7 is a contact layer, 8 is a p-side electrode, and 9 is an n-side electrode. Here, a double hetero junction is formed by the lower cladding layer 4, the active layer 3, and the upper cladding layer 5, and a stripe region is defined by the current blocking layer 6. In FIG. 3, the substrate 2 is made of GaAs, and the active layer 3 is made of GaInAsN. The current blocking layer 6 of this device is made of Si-doped GaAs.

In the semiconductor laser having the structure shown in FIG. 3, light can be vertically confined by the double hetero junction of the lower cladding layer 4, the active layer 3, and the upper cladding layer 5. In this type of semiconductor laser, confining injected carriers (in the example of FIG. 3, current injected from the p-side electrode 8 toward the active layer 3) and light in the horizontal direction with respect to the substrate is low. This is important for thresholding.
In this case, the InGaNAs-based material can emit light at a wavelength in the 1.3 μm or 1.5 μm band.
The bandgap energy with As is larger than that of the InGaNAs-based material, it is transparent to long-wavelength light, and does not become an anti-waveguide layer.

Therefore, in the example of FIG.
Is provided, and the current block layer 6 is provided to form a stripe region (a region where the current block layer 6 is not provided).
Is thicker than the outside of the stripe region (the region below the current block layer 6), a difference in refractive index of light is generated between the stripe region and the outside of the stripe region, and light can be confined in the stripe region.

[0012]

However, in the device shown in FIG. 3, after the first growth (after forming the double hetero junction), a ridge stripe portion is formed, and then a current blocking layer is grown (FIG. 3). Epitaxial growth must be performed in three steps, such as growing the contact layer (the second growth) and then growing the contact layer (the third growth), which causes a problem that the fabrication becomes complicated.

An object of the present invention is to provide a semiconductor light emitting device having a good temperature characteristic, a long wavelength, and a structure easy to manufacture.

[0014]

According to a first aspect of the present invention, there is provided a semiconductor light emitting device formed on a GaAs substrate, wherein the active layer comprises a material having a smaller band gap energy than GaAs. And a layer formed in the vicinity of the active layer and absorbing light emitted by the active layer.

According to a second aspect of the present invention, in the semiconductor light emitting device according to the first aspect, a layer that absorbs light emitted by the active layer is formed without contacting the active layer. And

According to a third aspect of the present invention, an active layer made of a material having a smaller bandgap energy and a larger refractive index than GaAs is provided on a GaAs substrate of the first conductivity type. A first conductivity type lower cladding layer, which is provided between the GaAs substrate and the active layer and is made of a material having a larger band gap energy and a lower refractive index than the active layer, and the substrate as viewed from the active layer; A first upper cladding layer of a second conductivity type, which is provided on the opposite side and has a higher band gap energy and a lower refractive index than the active layer;
A second conductivity type second upper cladding layer provided on the opposite side to the substrate when viewed from the first upper cladding layer; and a second conductivity type second upper cladding layer provided on the opposite side to the substrate when viewed from the second upper cladding layer. A contact layer of the second conductivity type, and a current blocking layer of the first conductivity type provided at a portion between the first upper clad layer and the second upper clad layer to constrict current; The current blocking layer is made of a material having a smaller band gap energy than GaAs, and also has a function as a layer for absorbing light emitted from the active layer.

According to a fourth aspect of the present invention, in the semiconductor light emitting device according to the third aspect, the current blocking layer comprises:
It is characterized in that the group V element is a group III-V mixed crystal semiconductor layer made of N (nitrogen) containing _{III- (N x, V 1-} x).

According to a fifth aspect of the present invention, an active layer made of a material having a smaller bandgap energy and a higher refractive index than GaAs is provided on a first conductivity type GaAs substrate. A first conductivity type lower cladding layer, which is provided between the GaAs substrate and the active layer and is made of a material having a larger band gap energy and a lower refractive index than the active layer, and the substrate as viewed from the active layer; Are provided on the opposite side, and have a second conductive type first upper cladding layer made of a material having a larger bandgap energy and a lower refractive index than the active layer, and the substrate as viewed from the first upper cladding layer. A second upper cladding layer of a second conductivity type provided on the opposite side, and a second conductivity type provided on the opposite side of the substrate as viewed from the second upper cladding layer; A contact layer, a first conductivity type current blocking layer provided at a part between the first upper cladding layer and the second upper cladding layer, for narrowing a current, the current blocking layer and the first current blocking layer; A light absorbing layer provided between the upper cladding layer or between the current blocking layer and the second upper cladding layer;
It is made of a material having a smaller band gap energy than GaAs, and has a function of absorbing light emitted by the active layer.

According to a sixth aspect of the present invention, in the semiconductor light emitting device according to the fifth aspect, the light absorbing layer includes III- (N _x , V _1-x ) containing a group V element containing N (nitrogen). III)
It is a group V mixed crystal semiconductor layer.

According to a seventh aspect of the present invention, there is provided the semiconductor light emitting device according to the fourth or sixth aspect, wherein
-( _Nx , V1 _-x ) III-V mixed crystal semiconductor layer is composed of In
_x Ga _{1 -x} N _y As _{1 -y} (0 <x <1, 0 <y <1).

[0021]

Embodiments of the present invention will be described below with reference to the drawings. The semiconductor light emitting device of the present invention,
An active layer formed on a GaAs substrate and made of a material having a lower band gap energy than GaAs;
A layer formed near the active layer and absorbing light emitted by the active layer. In this case, the layer that absorbs light emitted from the active layer is formed without being in contact with the active layer.

FIG. 1 is a view showing a configuration example of a semiconductor light emitting device (semiconductor laser device) according to the present invention. Referring to FIG. 1, this semiconductor light emitting device includes an active layer 105 made of a material having a smaller band gap energy and a larger refractive index than GaAs on a GaAs substrate 101 of a first conductivity type. GaAs substrate 10
1 between the active layer 105 and the active layer 105.
The first conductive type lower cladding layer 103 made of a material having a larger bandgap energy and a smaller refractive index than that of the first conductive layer 105 and the substrate 101 viewed from the active layer 105.
A second conductive type first upper cladding layer 107 made of a material having a larger band gap energy and a smaller refractive index than the active layer 105,
The substrate 101 viewed from the first upper cladding layer 107
A second conductive type second upper cladding layer 109 provided on the side opposite to the first conductive type, and a second conductive type contact layer 110 provided on the side opposite to the substrate when viewed from the second upper clad layer 109. A current blocking layer 108 of a first conductivity type which is provided between the first upper cladding layer 107 and the second upper cladding layer 109 and narrows a current. Is made of a material having a smaller band gap energy than GaAs,
5 also has a function as a layer that absorbs the light emitted in 5.

The current blocking layer 108 is made of III- (N _x , V _1-x ) containing N (nitrogen) as a group V element.
III- (N _x , V _1-x )
Group III-V mixed crystal semiconductor layer made of, specifically, an In _x
Ga _1-x N _y As _1-y (0 <x <1, 0 <y <1).

The semiconductor light emitting device shown in FIG.
On an n-GaAs substrate 101, an n-GaAs buffer layer 102, an n-AlGaAs lower cladding layer 103, Ga
As light guide layer 104, InGaNAs active layer 105,
A GaAs light guide layer 106, a first upper cladding layer 107 of p-AlGaAs, and an n-InGaNAs anti-waveguide layer / current block layer 108 are formed.

Here, in the n-InGaNAs anti-waveguide layer and current blocking layer 108, a portion to be a stripe region is removed in the process of manufacturing this semiconductor light emitting device, and the first upper cladding layer 107 is formed in this portion. Is exposed.

Also, in the semiconductor light emitting device of FIG. 1, a portion to be a stripe region is removed, and the first upper cladding layer 107 is exposed in this portion. A second upper cladding layer 109 of p-AlGaAs and a p-GaAs contact layer 110 are formed on the current / blocking layer 108. That is, the entire device has a SCH-SQW structure as a layer structure and a SAS (Self-Aligned Structure Laser) type as a device structure.

In the semiconductor light emitting device shown in FIG. 1, AuZn / Au as the p-side electrode 111 is formed on the surface of the device, and AuGe as the n-side electrode 112 is formed on the back surface of the device.
/ Ni / Au.

The semiconductor light emitting device shown in FIG. 1 is manufactured by the following procedure. That is, first, the n-GaAs buffer layer 102 and the n-AlGaAs lower cladding layer 10 are formed on the n-GaAs substrate 101 by MOCVD.
3, GaAs light guide layer 104, InGaNAs active layer 105, GaAs light guide layer 106, p-AlGaAs
A first upper cladding layer 107 and an n-InGaNAs anti-waveguide layer / current blocking layer 108 are formed (first growth). Here, the raw material of N of InGaNAs includes:
DMHy (dimethylhydrazine) was used. Then, a portion to become a stripe region in the n-InGaNAs anti-waveguide layer and current block layer 108 is removed by wet etching or the like.

Next, the second upper cladding layer 109 of p-AlGaAs and the p-GaAs contact are formed on the n-InGaNAs anti-waveguide layer and current blocking layer 108 from which the portions to become the stripe regions have been removed as described above. Layer 11
Grow 0 (perform second growth).

Next, the AuZn / p-side electrode 111
Au is formed, and AuGe / Ni / Au serving as the n-side electrode 112 is formed on the back surface of the device, whereby the semiconductor light emitting device of FIG. 1 can be manufactured.

As described above, the semiconductor light emitting device of FIG.
It can be formed by multiple crystal growths.

Next, the characteristics and operating principle of the semiconductor light emitting device (semiconductor laser device) shown in FIG. 1 will be described. In general,
When several percent of N is added to InGaAs, the lattice constant decreases and the band gap energy decreases. That is, when N is added to InGaAs by several percent, crystals corresponding to long wavelengths such as 1.3 μm and 1.5 μm that are lattice-matched to the GaAs substrate can be formed. Further, the refractive index is GaAs
Greater than.

In the semiconductor light emitting device shown in FIG.
Since InGaNAs is used for the active layer 105, the active layer 105
It is lattice-matched to the GaAs substrate 101, can be formed on the GaAs substrate 101, and has an oscillation wavelength of, for example, 1.3 μm.
A long wavelength of about m can be obtained. In this case, AlGaAs having a large band gap energy is used.
Since the layer can be used as a cladding layer, the band discontinuity (ΔE _c ) of the conduction band increases, the overflow of injected carriers can be reduced, the threshold current can be reduced, and the temperature Dependency can be reduced.

The InGaNAs anti-waveguide layer and current blocking layer 108 has the same composition as the active layer 105.
Since it absorbs 1.3 μm light, it becomes an anti-waveguide layer (a layer that absorbs light emitted by the active layer). For this reason, a refractive index difference occurs between the stripe region and the outside of the stripe region, and light can be confined in the stripe region. That is,
A refractive index guided semiconductor laser can be formed.

As described above, the semiconductor light emitting device of FIG. 1 has a good temperature characteristic and a structure capable of increasing the wavelength as in the semiconductor light emitting device of FIG.
It has a structure in which the manufacturing process is easier than that of the element of FIG.

That is, the element (SBR laser) of FIG.
A double heterojunction structure is grown (first growth), and then the current block layer is selectively grown by mesa etching (second growth), and then a contact layer is grown.
(Third growth) is formed, but in the device of FIG. 1, there is no need to form a mesa portion and perform buried growth, and the number of times of growth is one less than that of the device of FIG. Times) and the device can be easily manufactured.

In the above example, the cladding layer is made of GaAs.
Although AlGaAs lattice-matched to the substrate was used, other than InGaAs such as InGaP lattice-matched to the GaAs substrate.
aAsP-based materials can also be used. InGaAsP
Since the base material does not contain active Al, AlGaAs
Preferred as in s. When InGaP is used, heat treatment is performed in an AsH ₃ atmosphere, and then the group V raw material is
Switch to H _3. When InGaAsP is used, heat treatment is performed in an AsH ₃ atmosphere, and then AsH ₃ + PH
You only need to grow it to ₃ , for example. Of course, crystal growth and heat treatment can be performed by MBE or the like in addition to MOCVD.

The active layer is made of a material capable of absorbing light emitted from the active layer by the InGaNAs anti-waveguide layer and current blocking layer, such as InGaAs, AlGaAs, and InGaAs.
sP or the like can be used. The device structure can be applied not only to the SAS structure but also to an element having a structure in which an effective refractive index distribution is formed by other anti-waveguide layers to confine light.

FIG. 2 is a diagram showing another configuration example of the semiconductor light emitting device according to the present invention. Referring to FIG. 2, this semiconductor light emitting device includes an active layer 10 made of a material having a smaller band gap energy and a larger refractive index than GaAs on at least a GaAs substrate 101 of a first conductivity type.
5, a GaAs substrate 101 of the first conductivity type and the active layer 1
The lower cladding layer 103 of the first conductivity type, which is provided between the active layer 105 and the active layer 105 and has a higher bandgap energy and a lower refractive index than the active layer 105, and the substrate 101 as viewed from the active layer 105. A second conductive type first upper cladding layer 107 provided on the opposite side and made of a material having a larger bandgap energy and a lower refractive index than the active layer 105; and the substrate as viewed from the first upper cladding layer. Is a second conductive type second upper cladding layer 109 provided on the opposite side, and a second conductive type contact layer 110 provided on the opposite side of the substrate 101 as viewed from the second upper cladding layer 109. A first conductivity type current blocking layer 2 provided at a portion between the first upper cladding layer 107 and the second upper cladding layer 109 for narrowing a current. 1 and a light absorbing layer 202 provided between the current blocking layer 201 and the first upper cladding layer 107. The light absorbing layer 202 is made of a material having a smaller band gap energy than GaAs. ,
It has a function of absorbing light emitted from the active layer 105.

Here, the light absorption layer 202 is formed by adding V
(Nitrogen) containing III- configured as group III-V mixed crystal semiconductor layer formed of _{(N x, V 1-x} ), III- III-V group mixed crystal consisting of _{(N x, V 1-x} ) The semiconductor layer is made of In _x Ga _1-x N _y As
_1-y (0 <x <1, 0 <y <1).

The semiconductor light emitting device shown in FIG.
N-InGaNAs anti-waveguide layer and current blocking layer 1 of FIG.
08 instead of InGaNAs anti-waveguide layer (light absorbing layer) 2
02 and an n-GaAs current block layer 201 are provided. In this case, the current blocking layer 20
1. In the anti-waveguide layer 202, a portion to be a stripe region is removed by, for example, wet etching.

The semiconductor light emitting device shown in FIG. 2 is manufactured by the following procedure. That is, first, the n-GaAs buffer layer 102 and the n-AlGaAs lower cladding layer 10 are formed on the n-GaAs substrate 101 by MOCVD.
3, GaAs light guide layer 104, InGaNAs active layer 105, GaAs light guide layer 106, p-AlGaAs
Forming a first upper cladding layer 107, an InGaNAs anti-waveguide layer 202, and an n-GaAs current blocking layer 201;
(Perform the first growth). Then, the InGaNAs anti-waveguide layer 202, n-GaAs are formed by wet etching or the like.
In the s current block layer 201, a portion to be a stripe region is removed.

Next, the n-GaAs current blocking layer 2 from which a portion to be a stripe region is removed as described above.
01, a second upper cladding layer 1 of p-AlGaAs
09, grow p-GaAs contact layer 110
(Do the second growth).

Next, the AuZn / p-side electrode 111
Au is formed, and AuGe / Ni / Au serving as the n-side electrode 112 is formed on the back surface of the device, whereby the semiconductor light emitting device of FIG. 2 can be manufactured.

As described above, the semiconductor light emitting device of FIG. 2 can be formed by two crystal growths, similarly to the semiconductor light emitting device of FIG.

Next, the characteristics and operating principle of the semiconductor light emitting device (semiconductor laser) shown in FIG. 2 will be described. The semiconductor light emitting device of FIG. 2 also has an active layer 1 similar to the semiconductor light emitting device of FIG.
Since InGaNAs is used for the active layer 105,
Are lattice-matched to the GaAs substrate 101,
It can be formed on the substrate 101 and has an oscillation wavelength of, for example, 1.
Long wavelengths of about 3 μm can be obtained. Also,
In this case, AlGa having a large band gap energy is used.
Since the As layer can be used as the cladding layer, the band discontinuity (ΔE _c ) of the conduction band increases, the overflow of the injected carriers can be reduced, the threshold current can be reduced, and Temperature dependence can be reduced.

The InGaNAs anti-waveguide layer 202 is
Since it has the same composition as the active layer 105 and absorbs 1.3 μm light, it becomes an anti-waveguide layer (a layer that absorbs light emitted by the active layer). For this reason, a refractive index difference occurs between the stripe region and the outside of the stripe region, and light can be confined in the stripe region. That is, a refractive index guided semiconductor laser can be formed.

As described above, the semiconductor light emitting device of FIG. 2 also has a structure capable of achieving a longer wavelength with good temperature characteristics, similarly to the semiconductor light emitting device of FIG. The structure of the device is easier than that of the device of No. 3.

That is, in the device of FIG. 2, the number of times of growth is one less than that of the device of FIG. 3, and the device can be easily manufactured.

In the above example, the cladding layer is made of GaAs.
Although AlGaAs lattice-matched to the substrate was used, other than InGaAs such as InGaP lattice-matched to the GaAs substrate.
aAsP-based materials can also be used.

The active layer is made of a material capable of absorbing light with the InGaNAs anti-waveguide layer, for example, InGaAs or AlGa.
As, InGaAsP or the like can be used. If the light emitted from the active layer 105 can be absorbed by the anti-waveguide layer 202, the current blocking layer 201 and the antiwaveguide layer 202
The order of lamination may be reversed. That is, in the example of FIG. 2, the light absorbing layer (anti-waveguide layer) 202 is provided between the current blocking layer 201 and the first upper cladding layer 107. It may be provided between the second upper cladding layer 109 and the second upper cladding layer 109. Also,
The device structure can be applied to an element having a structure in which an effective refractive index distribution is formed by another anti-waveguide layer to confine light.

As described above, according to the present invention, the layer that absorbs light emitted from the active layer is made of a group III element containing N (nitrogen).
- configured as group III-V mixed crystal semiconductor layer formed of _{(N x, V 1-x} ), III- a group III-V mixed crystal semiconductor layer formed of _{(N x, V 1-x} ), In x Ga _1-x N _y As _1-y (0 <x <1, 0 <y <
Since it is formed in 1), even in a semiconductor light emitting device using a material (for example, an InGaNAs-based material) having a smaller band gap energy and a larger refractive index than GaAs of a GaAs substrate for an active layer, the light emitted from the active layer is emitted as described above. Light can be absorbed by the semiconductor layer, and a refractive index guided light-emitting element can be formed. Therefore, there is no need to form a mesa portion and perform selective burying growth as in the conventional SBR laser, and the number of times of growth is reduced by one, and a refractive index waveguide having a good temperature characteristic and a longer wavelength can be obtained. Type light emitting element (for example, In
(GaNAs-based devices) can be easily manufactured.

[0053]

As described above, in the semiconductor light emitting device according to the first and second aspects, the active layer made of a material having a smaller band gap energy than GaAs absorbs light emitted from the active layer. , It is possible to provide a semiconductor light emitting device having a good temperature characteristic, a longer wavelength, and a structure easy to manufacture.

In the semiconductor light emitting device according to the third aspect, at least Ga is formed on the GaAs substrate of the first conductivity type.
An active layer made of a material having a lower bandgap energy and a higher refractive index than that of As;
a first conductivity type lower cladding layer, which is provided between an aAs substrate and the active layer, is made of a material having a larger bandgap energy and a smaller refractive index than the active layer, and the substrate as viewed from the active layer. Are provided on the opposite side, and are made of a material having a higher bandgap energy and a lower refractive index than the active layer.
An upper cladding layer, a second conductivity-type second upper cladding layer provided on a side opposite to the substrate when viewed from the first upper cladding layer, and opposite to the substrate when viewed from the second upper cladding layer A contact layer of the second conductivity type provided on the side,
A current blocking layer of a first conductivity type, provided at a portion between the first upper cladding layer and the second upper cladding layer, for confining a current;
It is made of a material having a smaller bandgap energy than s, and also has a function as a layer for absorbing light emitted from the active layer. A refractive index guided light emitting element having a structure in which an effective refractive index difference is provided between a region where a block layer is not provided and a region where a current block layer is provided can be provided.

Further, in the semiconductor light emitting device according to the fifth aspect, at least Ga is formed on the GaAs substrate of the first conductivity type.
An active layer made of a material having a lower bandgap energy and a higher refractive index than that of As;
a first conductivity type lower cladding layer, which is provided between an aAs substrate and the active layer, is made of a material having a larger bandgap energy and a smaller refractive index than the active layer, and the substrate as viewed from the active layer. Are provided on the opposite side, and have a second conductive type first upper cladding layer made of a material having a larger bandgap energy and a lower refractive index than the active layer, and the substrate as viewed from the first upper cladding layer. A second conductive type second upper cladding layer provided on the opposite side, a second conductive type contact layer provided on the opposite side of the substrate as viewed from the second upper cladding layer, and the first upper part; A current blocking layer of a first conductivity type, which is provided at a portion between the cladding layer and the second upper cladding layer, for constricting current; and between the current blocking layer and the first upper cladding layer. A light absorbing layer provided between the current blocking layer and the second upper cladding layer, wherein the light absorbing layer is made of a material having a band gap energy smaller than that of GaAs; Has a function to absorb light, so that the light emitted from the active layer seeps into the light absorbing layer to provide an effective refractive index difference between the region where the current block layer is not provided and the region where the current block layer is provided. Of the present invention can be formed.

Further, in the semiconductor light emitting device according to the fourth and sixth aspects, the layer for absorbing the light emitted by the active layer includes:
A group III-V mixed crystal semiconductor layer made of III- (N _x , V _1-x ) containing N (nitrogen) as a group V element is used.
Since lattice matching with the aAs substrate is possible, a layer for absorbing light can be formed to a sufficient thickness without generating misfit dislocations and the like, and light emitted from the active layer can be sufficiently absorbed. be able to.

In the semiconductor light emitting device according to the present invention, the III-V mixed crystal semiconductor layer made of III- (N _x , V _1-x ) containing N (nitrogen) as a group V element includes: In _x Ga _1-x N _y A
s _1-y (0 <x <1, 0 <y <1) and In _x G
If N is added to a _1-x As (0 <x <1), lattice matching with a GaAs substrate can be achieved with a small N composition, so that a layer that absorbs light emitted from the active layer can be easily formed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a semiconductor light emitting device according to the present invention.

FIG. 2 is a diagram showing another configuration example of the semiconductor light emitting device according to the present invention.

FIG. 3 is a diagram showing a conventional long wavelength semiconductor laser formed on a GaAs substrate.

[Explanation of symbols]

Reference Signs List 101 n-GaAs substrate 102 n-GaAs buffer layer 103 n-AlGaAs lower cladding layer 104 GaAs light guide layer 105 InGaNAs active layer 106 GaAs light guide layer 107 p-AlGaAs first upper cladding layer 108 n-InGaNAs anti-waveguide layer Current blocking layer 109 p-AlGaAs second upper cladding layer 110 p-GaAs contact layer 111 p-side electrode 112 n-side electrode 201 n-GaAs current blocking layer 202 InGaNAs anti-waveguide layer

Claims (7)

[Claims] 1. A semiconductor light emitting device formed on a GaAs substrate, comprising: an active layer made of a material having a smaller bandgap energy than GaAs; and an active layer formed near the active layer and absorbing light emitted by the active layer. A semiconductor light-emitting device comprising: 2. The semiconductor light emitting device according to claim 1, wherein the layer that absorbs light emitted by the active layer is formed without contacting the active layer. 3. An active layer made of a material having a lower band gap energy and a higher refractive index than GaAs on a GaAs substrate of a first conductivity type.
Provided between the conductive type GaAs substrate and the active layer,
A lower cladding layer of a first conductivity type made of a material having a larger bandgap energy and a smaller refractive index than the active layer; and a lower cladding layer provided on a side opposite to the substrate when viewed from the active layer; A second conductive type first upper clad layer made of a material having a large energy and a small refractive index; and a second conductive type second clad layer provided on a side opposite to the substrate when viewed from the first upper clad layer.
An upper cladding layer, a second conductivity type contact layer provided on the opposite side to the substrate when viewed from the second upper cladding layer, and one contact between the first upper cladding layer and the second upper cladding layer. A current blocking layer of a first conductivity type for confining a current, wherein the current blocking layer is
A semiconductor light emitting device comprising a material having a smaller band gap energy than GaAs, and also having a function as a layer for absorbing light emitted from an active layer. 4. The semiconductor light-emitting device according to claim 3, wherein the current blocking layer is formed of a III-V group composed of III- (N _x , V _1-x ) containing a group V element containing N (nitrogen). A semiconductor light-emitting device comprising a crystalline semiconductor layer. 5. An active layer made of a material having a smaller band gap energy and a larger refractive index than GaAs on a GaAs substrate of a first conductivity type.
Provided between the conductive type GaAs substrate and the active layer,
A lower cladding layer of a first conductivity type made of a material having a larger bandgap energy and a smaller refractive index than the active layer, and a lower cladding layer provided on a side opposite to the substrate when viewed from the active layer; A second conductive type first upper clad layer made of a material having a large gap energy and a small refractive index; and a second conductive type second upper clad layer provided on a side opposite to the substrate when viewed from the first upper clad layer. An upper cladding layer, a second conductivity type contact layer provided on the opposite side to the substrate when viewed from the second upper cladding layer, and one contact between the first upper cladding layer and the second upper cladding layer. A current blocking layer of a first conductivity type for confining current, between the current blocking layer and the first upper cladding layer, or between the current blocking layer and the second upper cladding layer. A light absorbing layer provided between the active layer and the light absorbing layer, the light absorbing layer being made of a material having a smaller band gap energy than GaAs, and having a function of absorbing light emitted from the active layer. A semiconductor light emitting device characterized by the above-mentioned. 6. The semiconductor light emitting device according to claim 5, wherein the light absorbing layer includes a group V element containing N (nitrogen).
A semiconductor light emitting device comprising a group III-V mixed crystal semiconductor layer comprising-(N _x , V _1-x ). 7. The semiconductor light emitting device according to claim 4, wherein said III- (N _x , V _1-x ) comprises
The group V mixed crystal semiconductor layer is composed of In _x Ga _1-x N _y As _1-y (0 <x
<1,0 <y <1).