JP2003324242A - Semiconductor laser device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DFB semiconductor laser device oscillated by a single wavelength. <P>SOLUTION: A DFB laser device 100 is provided with an n-type InP substrate 101, V grooves 102 having specific periods, diffraction regions 103 composed of InNAsP and formed so as to be padded in respective V grooves 102, an n-type InP clad layer 104, an active region 105, and a p-type In clad layer 106. The active region 105 has multiple-quantum well structure and its absorption end wavelength is 1.55μm. The diffraction regions 103 are formed so as to be embedded in the V grooves 102 and each of their absorption end wavelengths is 1.60μm. Since the diffraction regions 103 have the functions for absorbing light radiated from the active region 105, the laser oscillation of a single wavelength can be obtained. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor laser device.

[0002]

2. Description of the Related Art An optical fiber communication system has been put into practical use as a communication system which has an extremely high speed and can use a wide band. As a light source used in an optical fiber communication system, an InP substrate and In that is lattice-matched to the InP substrate
A semiconductor laser device using a GaAsP mixed crystal is being actively developed.

Distributed feedback semiconductor laser device (hereinafter referred to as DF
It is difficult to manufacture a diffractive structure provided for diffracting a laser beam in manufacturing a B laser device). Further, in the DFB laser device, the probability of laser oscillation at a single wavelength is low. Therefore, it is a factor of increasing the manufacturing cost of the DFB laser device. So D
There is a demand for an easy method of manufacturing an FB laser device and an improvement in the probability of laser oscillation at a single wavelength.

A conventional DFB laser device will be described below with reference to FIG. FIG. 6 is a sectional view taken along the waveguide showing the structure of a conventional DFB laser device.

As shown in FIG. 6, a DFB laser device 30 is provided.
0 is an n-type InP substrate 301 and an n-type InP substrate 301
A V-groove 302 provided with a depth of 100 nm and a pitch of 244 nm, a diffraction region 303 made of InAsP formed so as to fill each V-groove 302, and formed over the V-groove 302 and the diffraction region 303. Thickness 200n
An n-type InP clad layer 304 having a thickness of m, an active region 305 having a thickness of 200 nm, and a p-type InP clad layer 306 having a thickness of 400 nm are provided. In addition, the n-type InP substrate 30
N-type electrode 307 is formed on the lower surface of p.
A p-type electrode 308 is formed on the upper surface of the clad layer 306.

The active region 305 is composed of five layers of InGaAsP.
Quantum well layers and four InGaAsP barrier layers are alternately formed, and these are further two layers of InGaAs.
It has a structure sandwiched between P light confinement layers. InGaAs
The P quantum well layer has a compressive strain of 1% and has a thickness of 6 nm, and its band gap converted into wavelength (that is, absorption edge wavelength) is 1.55 μm. InGaAsP
The barrier layer is lattice-matched to InP and has a thickness of 10 nm,
Its absorption edge wavelength is 1.15 μm. InGaAsP
The light confinement layer has a thickness of 60 nm and its absorption edge wavelength is 1.15 μm.

The size of the diffraction region 303 made of InAsP in the depth direction is 40 nm and is formed so as to be embedded in the V groove 302. The composition of the diffraction region 303 is I
nAs _0.1 P _0.9 and its absorption edge wavelength is 1.40 μm
Has become.

[0008]

In the DFB laser device, the probability of laser oscillation at a single wavelength depends on the diffraction and absorption by the diffraction region formed near the active region. Particularly, in the above-mentioned conventional DFB laser device 300, since the absorption edge wavelength of the diffraction region 303 is shorter than the laser oscillation wavelength, the laser beam is not absorbed in the diffraction region 303, and the probability of laser oscillation at a single wavelength. Is low.

Therefore, in the conventional DFB laser device 300, the diffraction region 303 is formed so that the absorption edge wavelength of the diffraction region 303 is longer than the laser oscillation wavelength.
By absorbing the laser beam in the diffractive region 303, it is possible to oscillate with a single wavelength with high probability. As a method of shifting the absorption edge wavelength of the diffraction region 303 to a long wavelength, InA forming the diffraction region 303 is used.
There is a method of adjusting the composition ratio of As and P of sP.

However, in order to set the absorption edge wavelength of the diffraction region 303 to 1.55 μm or more, which is the wavelength band for optical communication, A of InAsP constituting the diffraction region 303 is set.
When the composition ratio of s and P is adjusted, the lattice constant of InAsP forming the diffraction region 303 becomes larger than the lattice constant of the n-type InP substrate 301. Therefore, a crystal defect occurs due to the lattice mismatch between the n-type InP substrate 301 and the InAsP forming the diffraction region 303, and the characteristics of the DFB laser device deteriorate.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a semiconductor laser device having good characteristics.

[0012]

A semiconductor laser device according to the present invention comprises a semiconductor substrate and a plurality of diffraction regions formed on the semiconductor substrate in parallel with each other and made of a III-V group compound semiconductor containing nitrogen. And an active region made of a compound semiconductor formed on the semiconductor substrate and over the plurality of diffraction regions, and the plurality of diffraction regions have a function of absorbing light emitted from the active region.

The absorption edge wavelength of the III-V group compound semiconductor containing nitrogen shifts to a longer wavelength than that of the III-V group compound semiconductor containing no nitrogen. Further, the lattice constant of the III-V group compound semiconductor is reduced by increasing the composition ratio of nitrogen. Therefore, by adjusting the composition ratio of nitrogen in the plurality of diffraction regions, the lattice constants of the plurality of diffraction regions can be brought close to the lattice constant of the semiconductor substrate having a small lattice constant, and the absorption edge wavelength can be shifted to a long wavelength. it can.
Therefore, according to the present invention, it is possible to obtain the semiconductor laser device in which the deterioration of the crystallinity of the diffraction region due to the lattice mismatch is suppressed and the laser oscillation is performed at a single wavelength with a high probability.

It is preferable that the plurality of diffraction regions and the lattice constant of the semiconductor substrate substantially match.

As a result, the deterioration of the crystallinity of the diffraction region due to the lattice mismatch is further suppressed.

The absorption edge wavelengths of the plurality of diffraction regions are equal to or larger than the oscillation wavelength of the active region.

As a result, the probability of laser oscillation at a single wavelength can be further improved.

The thickness of the plurality of diffraction regions is 100 nm.
And the absorption edge wavelengths of the plurality of diffraction regions are 1.
The configuration may be 3 μm or more.

The oscillation wavelength of the active region may be 1.3 μm or more and 1.6 μm or less.

The plurality of diffraction regions have a nitrogen composition ratio of 0.
%, And may be 2% or less.

The active region may have a clad layer below it.

The semiconductor substrate may have a plurality of grooves formed on its upper surface substantially parallel to each other, and the plurality of diffraction regions may be formed so as to fill the plurality of grooves.

The semiconductor substrate is InP or GaAs.
It may be configured as.

A method of manufacturing a semiconductor laser device according to the present invention comprises:
A step (a) of preparing a semiconductor substrate, a step (b) of forming a plurality of grooves on the semiconductor substrate, each groove extending in parallel with each other, and a heat treatment of the semiconductor substrate in an atmosphere containing a gas containing nitrogen. After forming a plurality of diffractive regions made of a III-V group compound semiconductor containing nitrogen filling the plurality of trenches, an active region made of a compound semiconductor is formed on the semiconductor substrate and the plurality of diffractive regions. Forming step (c).

The absorption edge wavelength of the III-V group compound semiconductor containing nitrogen shifts to a longer wavelength than that of the III-V group compound semiconductor containing no nitrogen. Further, the lattice constant of the III-V group compound semiconductor is reduced by increasing the composition ratio of nitrogen. Therefore, by adjusting the composition ratio of nitrogen in the plurality of diffraction regions, the lattice constants of the plurality of diffraction regions can be brought close to the lattice constant of the semiconductor substrate having a small lattice constant, and the absorption edge wavelength can be shifted to a long wavelength. it can.
Therefore, according to the present invention, it is possible to obtain the semiconductor laser device in which the deterioration of the crystallinity of the diffraction region due to the lattice mismatch is suppressed and the laser oscillation is performed at a single wavelength with a high probability.

In particular, in the manufacturing method of the present invention, the plurality of diffraction regions and the active region are formed continuously in one step, so that the manufacturing cost is reduced. Further, lattice defects, strains, cracks, etc. are unlikely to occur in the plurality of diffraction regions and active regions.

In the step (c), after forming the plurality of diffraction regions, a surface flattening layer made of a compound semiconductor is formed on the semiconductor substrate and the plurality of diffraction regions, and then the surface flattening layer is formed. The active region may be formed on the oxide layer.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Note that, for simplification, the components common to the respective embodiments are denoted by the same reference numerals.

(Embodiment 1) Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 shows the D of this embodiment.
It is a sectional view along a waveguide showing composition of an FB laser device.

As shown in FIG. 1, the DFB laser device 10
0 is the n-type InP substrate 101 and the n-type InP substrate 101
A V-groove 102 provided with a depth of 100 nm and a pitch of 244 nm, a diffraction region 103 made of InNAsP formed so as to fill each V-groove 102, and an n-type InP.
A 200-nm-thick n-type InP clad layer 104 formed over the substrate 101 and the diffraction region 103, a 200-nm-thick active region 105, and a 400-nm-thick p-layer.
And a type InP clad layer 106. An n-type electrode 107 is formed on the lower surface of the n-type InP substrate 101, and a p-type electrode 108 is formed on the upper surface of the p-type InP clad layer 106.

The active region 105 is composed of five layers of InGaAsP.
Quantum well layers and four InGaAsP barrier layers are alternately formed, and these are further two layers of InGaAs.
It has a structure sandwiched between P light confinement layers. InGaAs
The P quantum well layer has a compressive strain of 1%, has a thickness of 6 nm, and has an absorption edge wavelength of 1.55 μm. InGaA
The sP barrier layer is lattice-matched to the n-type InP substrate 101, has a thickness of 10 nm, and has an absorption edge wavelength of 1.15 μm. The InGaAsP optical confinement layer has a thickness of 60 nm and its absorption edge wavelength is 1.15 μm.

The size of the diffraction region 103 made of InNAsP in the depth direction is 40 nm and is formed so as to be embedded in the V groove 102. The composition of the diffraction region 103 is InN _0.02 As _0.18 P _0.80 , and its absorption edge wavelength is 1.60 μm.

Now, the relationship between the lattice constant and the band gap of the diffraction region will be described with reference to FIG. Figure 2 shows III-
It is a figure showing the correlation of the lattice constant and band gap of a V group compound semiconductor. Note that in FIG. 2, 0 ≦ x ≦ 1, 0
≦ y ≦ 1, and the point (x, y) = (0, 0) is InP
Then, InN _x P _1-x and InAs _y P _1-y are displayed as being separated from InP as x and y increase.

In the conventional distributed feedback laser device 300, the absorption edge wavelength of the InAsP diffraction region 303 is shorter than the laser oscillation wavelength of 1.55 μm (1.
40 μm), and since the diffraction region does not absorb light, the proportion of oscillation at a single wavelength is low. Therefore, in order to improve the single wavelength oscillation probability, the absorption edge wavelength of the diffraction region 303 is set to 1.
It is necessary to set a long wavelength of 55 μm or more. But,
In order to set the absorption edge wavelength to a long wavelength, the diffraction region 303
When the composition ratio of As is increased, as shown in a region R in FIG. 2, the diffraction region 303 has a lattice constant of n-type InP substrate 30.
It becomes larger than 1. Therefore, the diffraction region 303
In addition, the strain due to the lattice mismatch increases and the diffraction region 303
Lattice defects occur in the.

However, as shown in FIG. 2, the band gap of the diffraction region 103 is reduced by adding N and As to InP. That is, the absorption edge wavelength of the diffraction region 103 shifts to a long wavelength. Further, the lattice constant of InNAsP becomes larger by increasing the composition ratio of As, and becomes smaller by increasing the composition ratio of N. Therefore, by adjusting the composition ratio of As and N in the diffraction region 103, it becomes possible to perform lattice matching with InP and shift the absorption edge wavelength to a long wavelength. That is, according to the present embodiment, by forming the diffraction region 103 made of InNAsP, it is possible to suppress the deterioration of the crystallinity of the diffraction region 103 due to the lattice mismatch.

Therefore, according to this embodiment, it is possible to obtain a DFB laser device having a high probability of laser oscillation at a single wavelength.

In this embodiment, since the absorption edge wavelength of the InGaAsP quantum well layer is 1.55 μm, the absorption edge wavelength of the diffraction region 103 is 1.60 μm.
It is not limited to this. That is, the absorption edge wavelength of the diffraction region 103 is shifted to a long wavelength with respect to the laser oscillation wavelength determined by the band gap of the InGaAsP quantum well layer, and the diffraction region 103 and the n-type InP substrate 1 are
If 01 is substantially lattice-matched, the same effect as this embodiment can be obtained.

The amount of strain in the diffraction area 103 is preferably small. That is, it is preferable that the lattice mismatch between the InP substrate 101 and the diffraction region 103, which causes the distortion of the diffraction region 103, is small. Therefore, the composition of InNAsP forming the diffraction region 103 is InN _x (As
_{In y} P _1-y ) _1-x , the range of x is preferably 0 ≦ x ≦ 0.03, and the range of y is preferably 0 ≦ y ≦ 0.3.

The oscillation wavelength of the laser used for optical communication is 1.3 μm or 1.55 μm. Therefore,
When the DFB laser device 100 is used for optical communication, the absorption edge wavelength of the diffraction region 103 is 1.3 μm or more and 1.6 μm or more.
The following is preferable.

Further, by summing up the above preferable conditions,
It is particularly preferable to adjust the composition of InNAsP forming the diffraction region 103 so that the lattice constant and the absorption edge wavelength (band gap) of the diffraction region 103 exist in the shaded region F shown in FIG.

Further, the composition of the InNAsP forming the diffraction region 103 is adjusted so that the ratio (difference) of the lattice constant of the diffraction region 103 to the lattice constant of the n-type InP substrate 101 is ± 1% or less. More preferably.

Next, referring to FIG. 3, the DFB of the present embodiment will be described.
A method of manufacturing the laser device 100 will be described. 3A to 3D are process cross-sectional views along the waveguide showing the method of manufacturing the DFB laser device 100 of the present embodiment.

First, in the step shown in FIG. 3A, n-type In
On P substrate 101, depth 100nm, pitch 244nm
The V-shaped groove 102 extending in stripes is formed by photolithography and anisotropic etching using the two-beam interference exposure or the EB method.

Next, in the step shown in FIG. 3B, the substrate obtained in the above step is introduced into the MOVPE apparatus. Next, the temperature is raised to about 450 ° C., and phosphine, arsine,
By performing a heat treatment in a mixed gas containing dimethylhydrazine, In of the bottom of the V groove 102 having a height of 40 nm is formed.
A diffractive area 103 made of NAsP is formed. At this time, together with the source gases phosphine, arsine, and dimethylhydrazine, the portion indicated by T of the n-type InP substrate 101 is supplied into the V groove 102 as the source of In and P, and the diffraction region 103 is formed (mass transformer). Port phenomenon). At this time, the composition of the diffraction region 103 is I
The ratio of each gas in the raw material gas is adjusted so as to be nN _0.02 As _0.18 P _0.80 .

In this embodiment, the size of the diffraction region 103 made of InNAsP in the depth direction is 40 nm, but the size is not limited to this, and may be any size that does not cause lattice defects.

Then, the source gas is changed to phosphine and T
Change to mixed gas of MI, 200nm thick n-type InP
The clad layer 104 is formed. At this time, the upper surface of the n-type InP clad layer 104 is naturally flattened. continue,
Source gas phosphine, arsine, TMI and TE
5 layers of InG while changing the mixing ratio of G mixed gas
The aAsP quantum well layers and the four InGaAsP barrier layers are alternately formed, and these are further formed into two In layers.
An active region 105 having a structure sandwiched between GaAsP optical confinement layers is formed. Then, the source gas was changed to a mixed gas of phosphine and TMI, and a p-
A type InP clad layer 106 is formed.

Next, in the step shown in FIG. 3C, n-type In
An n-type electrode 107 is formed on the lower surface of the P substrate 101, and a p-type electrode 108 is formed on the upper surface of the p-type InP clad layer. As a result, the DFB laser device 100 is obtained.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view taken along the waveguide showing the configuration of the DFB laser device 200 of this embodiment.

As shown in FIG. 4, the DFB laser device 20
0 is the n-type InP substrate 201 and the n-type InP substrate 201
On top, each has a thickness of 50 nm and each has a width of 80
nm and a diffraction region 203 made of InNAsP provided so as to extend in a stripe shape with a pitch of 244 nm.
A 200-nm-thick n-type InP clad layer 204 formed over the n-type InP substrate 201 and the diffraction region 103, a 200-nm-thick active region 205, and a 400-nm-thick p-type InP clad layer 206. It has and. An n-type electrode 207 is formed on the lower surface of the n-type InP substrate 201, and a p-type electrode 208 is formed on the upper surface of the p-type InP clad layer 206.

The active region 205 is composed of five layers of InGaAsP.
Quantum well layers and four InGaAsP barrier layers are alternately formed, and these are further two layers of InGaAs.
It has a structure sandwiched between P light confinement layers. InGaAs
The P quantum well layer has a compressive strain of 1%, has a thickness of 6 nm, and has an absorption edge wavelength of 1.55 μm. InGaA
The sP barrier layer is lattice-matched to the n-type InP substrate 201, has a thickness of 10 nm, and has an absorption edge wavelength of 1.15 μm. The InGaAsP optical confinement layer has a thickness of 60 nm and its absorption edge wavelength is 1.15 μm.

The composition of the diffraction region 203 made of InNAsP is InN _0.02 As _0.18 P _0.80 , and its absorption edge wavelength is 1.60 μm.

That is, the DFB laser 1 of the first embodiment
00 is different only in that the diffraction regions 203 are provided in stripes on the n-type InP substrate 201.

According to this embodiment, by forming the diffraction region 203 made of InNAsP, it is possible to suppress the deterioration of the crystallinity of the diffraction region 203 due to the lattice mismatch. Therefore, according to this embodiment, a DFB laser device having a high probability of laser oscillation at a single wavelength can be obtained.

Next, referring to FIG. 5, the DFB of the present embodiment will be described.
A method of manufacturing the laser device 200 will be described. 5A to 5C are process cross-sectional views along the waveguide showing the method of manufacturing the DFB laser device 200 of the present embodiment.

First, in the step shown in FIG. 5A, n-type In
A P substrate 201 is prepared and introduced into a MOVPE device.
Next, MOVP using a mixed gas of phosphine, arsine, dimethylhydrazine and TMI as a source gas
A 50 nm thick InNAsP layer 202 is deposited by the E method. At this time, the composition of the InNAsP layer 202 is
The ratio of each gas in the source gas is adjusted so that InN _0.02 As _0.18 P _0.80 is obtained. In this embodiment, InNA
Although the thickness of the sP layer 202 is set to 40 nm, the thickness is not limited to this and may be equal to or smaller than the size at which lattice defects do not occur.

Next, in the step shown in FIG. 5B, photolithography and etching are performed to
Diffraction regions 203 extending in stripes with a pitch of 244 nm and each having a width of 80 nm are formed.

Next, in the step shown in FIG. 5C, M using a mixed gas of phosphine and TMI as a source gas.
By the OVPE method, n-type I is formed so as to cover the upper surface of the n-type InP substrate 201 and the upper surface and the side surface of the diffraction region 203.
The nP clad layer 204 is formed. The n-type InP clad layer 204 is grown until the thickness from the upper surface of the n-type InP substrate 201 becomes 200 nm. At this time, n-type In
The upper surface of the P clad layer 204 is naturally flattened. After that, while changing the mixing ratio of the mixed gas of phosphine, arsine, TMI, and TEG as the source gas, the I
An nGaAsP quantum well layer and four InGaAsP barrier layers are alternately formed, and these form an active region 205 having a structure sandwiched by two InGaAsP optical confinement layers. Then, the source gas is changed to a mixed gas of phosphine and TMI, and the thickness is 400 nm.
Then, the p-type InP clad layer 206 is formed.

Next, in the step shown in FIG. 5D, n-type In
An n-type electrode 207 is formed on the lower surface of the P substrate 201, and a p-type electrode 208 is formed on the upper surface of the p-type InP clad layer 206. As a result, the DFB laser device 200 is obtained.

The DFB laser device 20 of this embodiment is used.
Even at 0, the absorption edge wavelength of the diffraction region 203 is shifted to a long wavelength with respect to the laser oscillation wavelength determined by the band gap of the InGaAsP quantum well layer, and the diffraction region 203 and the n-type InP substrate 201 are If the structure is substantially lattice-matched, the same effect as that of the first embodiment can be obtained.

In the DFB laser device 200 of this embodiment, as in the case of Embodiment 1, the diffraction region 20 is also included.
The composition of InNAsP constituting No. 3 is InN _x (As _y P
_1-y ) _1-x , it is preferable that the range of x is 0 ≦ x ≦ 0.03 and the range of y is 0 ≦ y ≦ 0.3.

When the DFB laser device 200 is used for optical communication, the absorption edge wavelength of the diffraction region 203 is 1.3.
It is preferable that the thickness is in the range from μm to 1.6 μm.

Further, by summing up the above preferable conditions,
It is particularly preferable to adjust the composition of InNAsP forming the diffraction region 203 so that the lattice constant and the absorption edge wavelength (band gap) of the diffraction region 203 exist in the shaded region F shown in FIG.

The composition of InNAsP forming the diffraction region 203 is adjusted so that the ratio of the difference (deviation amount) of the lattice constant of the diffraction region 203 to the lattice constant of the n-type InP substrate 201 is ± 1% or less. More preferably.

In the manufacturing method of this embodiment, the diffraction region 203 and the active region 205 are separately formed (the process shown in FIG. 5B and the process shown in FIG. 5C).
Are individually formed by the MOVPE method.

On the other hand, in the manufacturing method of the first embodiment, the diffraction region 103 and the active region 105 are formed in one step (see FIG. 3).
In the step shown in (b), since the MOVPE method is used to continuously form the film, the manufacturing cost is reduced.

Further, as in the first embodiment, the diffraction area 1
03, the n-type InP clad layer 104, the active region 105, and the n-type InP clad layer 106 are continuously formed by the MOVPE method at one time in one step. Lattice defects, strains, cracks, etc. hardly occur in the region 105 and the n-type InP clad layer 106.

Furthermore, according to the manufacturing method of the first embodiment, the size and shape of the diffraction region 103 are determined by the amount of In supplied by the mass transport phenomenon.
It is easy to accurately manufacture the size and shape of the diffraction region 103.

Although the distributed feedback semiconductor laser device (DFB laser device) has been described in the first and second embodiments, the present invention is not limited to this. For example, also in the distributed Bragg reflector type semiconductor laser device, by providing the same diffraction region as in the first and second embodiments, exactly the same effect can be obtained.

[0069]

According to the present invention, a semiconductor laser device having good characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view taken along a waveguide showing the configuration of a DFB laser device according to a first embodiment.

FIG. 2 is a diagram showing a correlation between a lattice constant and a band gap of a III-V group compound semiconductor.

FIG. 3 is a process sectional view along a waveguide showing a method of manufacturing the DFB laser device according to the first embodiment.

FIG. 4 is a sectional view taken along the waveguide showing the configuration of the DFB laser device according to the second embodiment.

FIG. 5 is a process sectional view along a waveguide showing a method of manufacturing a DFB laser device according to a second embodiment.

FIG. 6 is a sectional view taken along a waveguide showing the structure of a conventional DFB laser device.

[Explanation of symbols]

100, 200, 300 DFB laser device 101, 201, 301 n-type InP substrate 102, 302 V groove 103, 203, 303 diffraction area 104, 204, 304 n-type InP clad layer 105, 205, 305 Active area 106, 206, 306 p-type InP clad layer 107, 207, 307 n-type electrode 108, 208, 308 p-type electrode 202 InNAsP layer

Claims (11)

[Claims] 1. A semiconductor substrate, a plurality of diffraction regions made of a III-V group compound semiconductor containing nitrogen, which are formed in parallel with each other on the semiconductor substrate, and on the semiconductor substrate and on the plurality of diffraction regions. And a plurality of active regions formed of a compound semiconductor, the plurality of diffraction regions having a function of absorbing light emitted from the active regions. 2. The semiconductor laser device according to claim 1, wherein the plurality of diffraction regions and the lattice constant of the semiconductor substrate are:
A semiconductor laser device characterized in that they substantially match. 3. The semiconductor laser device according to claim 1, wherein an absorption edge wavelength of the plurality of diffraction regions is equal to or larger than an oscillation wavelength of the active region. . 4. The semiconductor laser device according to claim 3, wherein the thickness of the plurality of diffraction regions is 100 nm or less, and the absorption edge wavelength of the plurality of diffraction regions is 1.3 μm or more. Characteristic semiconductor laser device. 5. The semiconductor laser device according to claim 4, wherein the oscillation wavelength of the active region is 1.3 μm or more and 1.6 μm or more.
A semiconductor laser device characterized by the following. 6. The semiconductor laser device according to claim 1, wherein the plurality of diffraction regions have a nitrogen composition ratio of more than 0% and 2% or less. Semiconductor laser device. 7. The semiconductor laser device according to claim 1, wherein the active region has a clad layer below the active region. 8. The semiconductor laser device according to claim 1, wherein the semiconductor substrate has a plurality of grooves formed substantially parallel to each other on an upper surface thereof, and the plurality of diffraction regions are provided. Are formed so as to fill the plurality of grooves. 9. The semiconductor laser device according to claim 1, wherein the semiconductor substrate is made of InP. 10. A step (a) of preparing a semiconductor substrate, a step (b) of forming a plurality of grooves on the semiconductor substrate, each groove extending in parallel to each other, and the step of: After performing a heat treatment on the semiconductor substrate to form a plurality of diffraction regions made of a III-V group compound semiconductor containing nitrogen that fills the plurality of grooves, a compound semiconductor is formed on the semiconductor substrate and the plurality of diffraction regions. A method of manufacturing a semiconductor laser device, comprising the step (c) of forming an active region made of. 11. The method of manufacturing a semiconductor laser device according to claim 10, wherein in the step (c), after forming the plurality of diffraction regions, the semiconductor substrate and the plurality of diffraction regions are formed.
A method of manufacturing a semiconductor laser device, comprising forming a surface flattening layer made of a compound semiconductor, and subsequently forming the active region on the surface flattening layer.