JP2001053383A - Semiconductor laser and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an equivalent refractive index difference, and to obtain fundamental transverse mode oscillation up to a high output, in a semiconductor laser having an internal current constriction structure. SOLUTION: On an n-type GaAs substrate 11, an In0.49Ga0.51P lower clad layer 12, an n (or i)-Inx2Ga1-x2As1-y2Py2 optical waveguide layer 13, an Inx3 Ga1-x3As1-y3Py3 compressive strain quantum well active layer 14, a p (or i)-Inx2 Ga1-x2As1-y2Py2 upper first optical waveguide layer 15, a p-Inx6Ga1-x6P first etching blocking layer 16 (0.2<=x6<=0.8), an n (or p)-Inx1Ga1-x1As1-y1Py1 second etching blocking layer 17, an n-In0.49Ga0.51P current constriction layer 18, an n-GaAs cap layer 19 are laminated. An SiO2 film 20 is formed on this, and the SiO2 film 20 in stripe regions about 3 μm wide is removed, and the cap layer 19 and the constriction layer 18 are etched. The SiO2 film is removed, and the cap layer 19 and the blocking layer 17 on the bottom surface of the groove are removed. On it, a p-Inx2Ga1-x2As1-y2Py2 upper second optical waveguide layer 21, a p-In0.49Ga0.51AsP upper clad layer 22, a p-GaAs contact layer 23 are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device and a method of manufacturing the same, and more particularly, to a semiconductor laser device having an internal current confinement structure and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor laser device of 0.9 μm to 1.1 μm, a current confinement layer has been widely provided inside a crystal layer in order to obtain fundamental transverse mode oscillation. For example, as a semiconductor laser device of a 0.98 μm band, n-
On a GaAs _{substrate, n-Al x Ga 1-} x As lower cladding layer, n-GaAs optical waveguide layer, InGaAs quantum well active layer, p-GaAs first upper optical waveguide _{layer, n-Al y Ga 1-} y
An As current confinement layer is laminated, and a narrow stripe groove extending through the n-AlGaAs current confinement layer is formed by normal photolithography using selective etching,
On top of that, a GaAs upper second optical waveguide layer, p-AlGaAs
There has been reported a semiconductor laser device having an internal stripe structure that oscillates in a fundamental transverse mode, wherein an upper clad layer and a p-GaAs contact layer are formed.

In this device, the controllability of the stripe groove width is high, and the n-AlGaAs current confinement layer and the p-GaAs
s Although the fundamental transverse mode oscillation is obtained up to a high optical output due to the difference in the refractive index from the upper second optical waveguide layer, A is easily oxidized.
There is a drawback that it is difficult to regrow AlGaAs on lGaAs, and an AlGaAs leakage current prevention layer is provided on both sides of the active layer because GaAs is used as the optical waveguide layer, but the leakage current is large and the threshold current is large. There were drawbacks.

[0004]

As described above, in a semiconductor laser device having a thickness of 0.9 μm to 1.1 μm, a leakage current is generated depending on a layer structure or its composition, and characteristics or reliability are optimized. Rather, it was difficult to obtain a fundamental transverse mode oscillation up to a high output. The present invention has been made in view of the above circumstances, and has as its object to provide a highly reliable semiconductor laser device that oscillates in a fundamental transverse mode even under high output.

[0005]

According to the semiconductor laser device of the present invention, a first conductivity type cladding layer, a lower optical waveguide layer, and a composition ratio of 0 <x3 ≦ 0.4 and 0 ≦ y3 are formed on a first conductivity type GaAs substrate.
In _x3 Ga _1-x3 As _{1-y3 Py 3} compressive strain quantum well active layer with ≦ 0.1, composition ratio x2 = (0.49 ± 0.01) y2 and 0 ≦ x2 ≦
A _{0.3 In x2 Ga 1-x2 As} 1-y2 P y2 first upper optical waveguide layer, the second conductivity type an In _x6 Ga composition ratio is 0.2 ≦ x6 ≦ 0.8
_1-x6 P first etching stop layer, striped portion serving as current injection window removed, composition ratio 0 ≦ x1 ≦ 0.3 and
In _x1 Ga _1-x1 As _1-y1 P _{y1 in} which 0 ≦ y1 ≦ 0.6 The first conductivity type In _0.49 Ga _0.51 P current confinement, in which the second etching stop layer and the striped portion serving as the current injection window have been removed. A composition ratio of x2 = (0.4
9 ± 0.01) The second conductivity type In _x2 G where y2 and 0 ≦ x2 ≦ 0.3
a _1-x2 As _1-y2 P _y2 Upper second optical waveguide layer, composition ratio x4 =
(0.49 ± 0.01) Second conductivity type In where y4 and 0.9 ≦ y4 ≦ 1
_{An x4} Ga1 _{-x4 As1 -y4 Py4} cladding layer and a second conductivity type contact layer are formed in this order, and the absolute value of the product of the strain amount and the film thickness of the compression-strained quantum well active layer is 0.25 nm or less. Where the absolute value of the sum of the product of the strain amount and the film thickness of the first etching stop layer and the product of the strain amount and the film thickness of the second etch stop layer is 0.25.
nm or less, and all the layers except the compression-strained quantum well active layer, the first etching stop layer and the second etching stop layer have a composition lattice-matched to the first conductivity type GaAs substrate. It is.

Further, another semiconductor laser device according to the present invention
Above and below the compressive strain quantum well active layer, which may be the _{In x5 Ga 1-x5 As 1} -y5 P y5 tensile strain barrier layer composition ratio is 0 ≦ x5 ≦ 0.3 and 0 <y5 ≦ 0.6 is formed, In this case, the absolute value of the sum of the product of the strain amount and the film thickness of the compression-strained quantum well active layer and the product of the strain amount of the tensile strain barrier layer and the total film thickness of the two tensile strain barrier layers is 0. It is desirable that the thickness be 25 nm or less.

[0007] The In _x1 Ga _1-x1 As _{1-y1 Py1} second etching stop layer may be of the first conductivity type or the second conductivity type.

Further, the width of the stripe may be 1 μm or more.

[0009] The compression-strained quantum well active layer may be composed of a plurality of quantum wells.

A method for manufacturing a semiconductor laser device according to the present invention
A first conductivity type clad layer on a first conductivity type GaAs substrate,
Lower optical waveguide layer, the composition ratio is 0 <x3 ≦ 0.4 and _{In x3 Ga 1-x3 As 1} -y3 P y3 compressive strain quantum well active layer is 0 ≦ y3 ≦ 0.1, the composition ratio x2 = (0.49 ± 0.01) y2 and In _x2 Ga _1-x2 As _1-y2 P _y2 with 0 ≦ x2 ≦ 0.3 Upper first optical waveguide layer, second conductivity type In _x6 Ga _1-x6 P with a composition ratio of 0.2 ≦ x6 ≦ 0.8 One etching stop layer, the composition ratio is 0 ≦ x1 ≦ 0.3 and 0 ≦ y1
In _x1 Ga _1-x1 As _1-y1 P _y1 second etching stop layer with ≦ 0.6, first conductivity type In _0.49 Ga _0.51 P current confinement layer,
A GaAs cap layer is laminated in this order, and a striped portion serving as a current injection window of the GaAs cap layer and the first conductivity type In _0.49 Ga _0.51 P current confinement layer is removed. GaAs removed
After simultaneously removing the stripe-shaped portion serving as the current injection window of the cap layer and the second etching stop layer, the current injection window is covered on the first conductivity type In _0.49 Ga _0.51 P current confinement layer. And the composition ratio is x2 = (0.49 ± 0.0
1) y2 and the second conductivity type In _x2 Ga _1-x2 satisfying 0 ≦ x2 ≦ 0.3
As _1-y2 P _y2 second upper optical waveguide layer, the composition ratio x4 = (0.49 ±
0.01) y4 and the second conductivity type In _x4 Ga satisfying 0.9 ≦ y4 ≦ 1
_{A 1-x4 As1 -y4 Py4} cladding layer and a second conductivity type contact layer are laminated in this order, and the absolute value of the product of the strain amount and the film thickness of the compressively strained quantum well active layer is set to 0.25 nm or less. The absolute value of the sum of the product of the strain amount and the film thickness of the etching stop layer and the product of the strain amount and the film thickness of the second etch stop layer is 0.25 nm or less, and the compressive strain quantum well active layer, the first etching stop layer, All the layers other than the second etching stop layer were replaced with the first conductivity type Ga.
It is characterized by lattice matching with an As substrate.

Further, the In _x1 Ga _1-x1 As _{1-y1 Py 1} second etching stop layer may be of a first conductivity type or a second conductivity type.

Further, the GaAs cap layer may be of the first conductivity type or the second conductivity type.

In addition, above and below the compression-strained quantum well active layer, In _x5 Ga whose composition ratio is 0 ≦ x5 ≦ 0.3 and 0 <y5 ≦ 0.6.
_{1-x5 As 1-y5 P} y5 tensile may be laminated strain barrier layer, in which case, the product of the strain amount and the film thickness of the compressive strain quantum well active layer, the strain amount of the cited tension strain barrier layer and the 2 It is desirable that the absolute value of the sum of the products of the total film thicknesses of the two tensile strain barrier layers be 0.25 nm or less.

Here, the strain amount of the compressively-strained quantum well active layer is represented by (ca−cs) / cs where the lattice constant of the GaAs substrate is cs and the lattice constant of the active layer is ca. Show.

The amount of strain of the etching stopper layer is Ga
Assuming that the lattice constant of the As substrate is cs and the lattice constant of the etching stopper layer is c e, a value represented by (ce−cs) / cs is shown.

The above lattice matching means that the value of (c−cs) / cs is 0.003 or less, where cs is the lattice constant of the GaAs substrate and c is the lattice constant of the growth layer. Show.

The strain amount of the tensile strain barrier layer is Ga
Let the lattice constant of the As substrate be cs and the lattice constant of the barrier layer be cb
Then, a value represented by (cb-cs) / cs is shown.

The first conductivity type and the second conductivity type are, for example, a p-type semiconductor having a polarity opposite to that of the first conductivity type if the first conductivity type is an n-type semiconductor. Things.

[0019]

According to the manufacturing method of the semiconductor laser device of the present invention, in particular, the current confinement layer and an In _0.49 Ga _0.51 P, the second upper optical waveguide layer as _{In x2 Ga 1-x2 As 1} -y2 P y2 As a result, an equivalent refractive index step caused by a difference in refractive index between the current confinement layer and the upper second optical waveguide layer can be accurately formed to about 1.5 to 7 × 10 ⁻³ , so that higher-order mode oscillation can be achieved. Can be easily realized. As a result, the fundamental transverse mode oscillation can be realized up to a high light output, and the reliability can be improved.

In a semiconductor laser device having a high light output, it is effective to reduce the peak density of the active layer by increasing the thickness of the optical waveguide layer in order to prevent the light emitting end face from being deteriorated due to the high light density. . However, in a semiconductor laser device having an internal confinement structure and a refractive index guiding mechanism, the thickness from the current confinement layer to the active layer must be increased in order to obtain a fundamental transverse mode with a lateral refractive index step. Therefore, there is a limit in increasing the thickness of the optical waveguide layer included therebetween. Therefore, as in the present invention, In _x2 Ga _1-x2 As _1-y2 having the same composition as the upper first waveguide layer is formed on the current confinement layer.
By forming the _Py2 second optical waveguide layer, the total thickness of the optical waveguide layer can be substantially increased. Thereby,
The peak density of the active layer can be reduced, deterioration of the light emitting end face due to high light density can be reduced, and reliability can be improved.

Further, the composition is In _x2 Ga _1-x2 As _1-y2 P
By forming the second optical waveguide layer of _y2 , the band gap difference between the active layer and the active layer can be made larger than before, so that leakage current can be prevented and carriers can be efficiently confined. Can be reduced.

Further, since the current confinement layer is provided inside, the contact area between the electrode and the contact layer can be increased, and the contact resistance can be reduced.

Further, In _x6 G is used as the first etching stopper layer.
a _1-x6 P, and In _x1 Ga on the second etching stopper layer
_{Since 1-x1} As _{1-y1 Py1} is used, in the case of a sulfuric acid-based etchant, only the second etch stop layer is etched and the first etch stop layer is not etched, so that the In _x6 Ga _1-x6 P It can be stopped on one etching stop layer, and the controllability of the stripe width by wet etching can be improved.

Further, since the composition of the interface layer forming the second optical waveguide layer does not contain Al, regrowth can be easily performed, and since there is no generation of defects due to oxidation of Al, deterioration of characteristics can be prevented. Can be.

In addition, In is formed above and below the compression-strained quantum well active layer.
_{x5 Ga 1-x5 As 1-} y5 case of forming a P _y5 tensile strain barrier layer, can be improved such as reduction of the threshold current, the various characteristics and reliability.

In a semiconductor laser device having a stripe width of 1 μm or more, it is more effective to apply the present invention having the above configuration, and a semiconductor laser which oscillates with low noise and high output even in a multimode is obtained. be able to.

According to the method of manufacturing a semiconductor laser device of the present invention, in particular, GaAs is formed on the InGaP current confinement layer.
By forming the s-cap layer, it is possible to prevent a natural oxide film from being formed on the InGaP current confinement layer or a layer denaturation caused by directly forming a resist layer. Further, by removing the GaAs cap layer before regrowth of the second clad layer, residues remaining at the regrowth interface can be removed, and generation of crystal defects can be prevented.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 illustrates a semiconductor laser device according to a first embodiment of the present invention along its manufacturing process.
FIG. 1 shows a cross-sectional view of the light emitting surface in the process of making the same.

As shown in FIG. 1A, an n-type GaAs substrate 11 is formed.
N-In _0.49 Ga _0.51 P by metal organic chemical vapor deposition
Lower cladding layer 12, n or i-In _x2 Ga _1-x2 As
_1-y2 P _y2 optical waveguide layer 13 (x2 = (0.49 ± 0.01) y2, 0 ≦ x2 ≦ 0.
3), compressive strain In _x3 Ga _1-x3 As _{1-y3 Py 3} quantum well active layer 14 (0 <x3 ≦ 0.4, 0 ≦ y3 ≦ 0.1), p or i-In
_{x2 Ga 1-x2 As 1-} y2 P y2 first upper optical waveguide layer 15, having a thickness of, for example, about _{10nm p-In x6 Ga 1-} x6 P first etching stop layer 16 (0.2 ≦ x6 ≦ 0.8) , the thickness of, for example 10nm approximately _{p-in x1 Ga 1-x1} As 1-y1 P y1 second etching stop layer 17 (0 ≦ x1 ≦ 0.3,0 ≦ y1 ≦ 0.6), thickness of, for example 1μ
An n-In _0.49 Ga _0.51 P current confinement layer 18 of m and an n-GaAs cap layer 19 having a thickness of, for example, about 10 nm are laminated.
An SiO ₂ film 20 is formed thereon, and the SiO ₂ film 20 in a stripe region having a width of about 3 μm is removed by ordinary lithography in the <011> direction.

Next, as shown in FIG. 1b, SiO ₂ film 20
As a mask, by etching the GaAs cap layer 19 with a sulfuric acid etchant, continue to etch the n-In _0.49 Ga _0.51 P current confinement layer 18 in a hydrochloric acid-based _{etchant, p-In x1 Ga 1-} x1 As 1-y1 The _Py1 second etch stop layer 17 is exposed.

[0032] Next, as shown in FIG. 1c, SiO ₂ film 20
Is removed with a hydrofluoric acid-based etchant, and subsequently with a sulfuric acid-based etchant, the n-GaAs cap layer 19 and the In _x1 Ga _1-x1 As _{1-y1 Py 1} second etching stop layer 17 on the bottom of the groove are removed.
To remove the p-In _x6 Ga _1-x6 P first etching stop layer
Expose 16.

Next, as shown in FIG. 1D, p-In _x2 G
a _1-x2 As _{1-y2 Py} 2 Upper second optical waveguide layer 21 (x2 = (0.49 ±
0.01) y2, 0 ≦ x2 ≦ 0.3), p-In _0.49 Ga _0.51 P upper cladding layer 22 and p-GaAs contact layer 23 are formed. A p-side electrode 24 is formed thereon, and the substrate is polished.
The side electrode 25 is formed. Thereafter, a high-reflectance coat and a low-reflectance coat are applied to the resonator formed by cleaving the sample, and thereafter, a semiconductor laser device is completed by chipping.

[0034] The thickness of the _{p-In x2 Ga 1-x2} As 1-y2 P y2 first upper optical waveguide layer 15 is the thickness of the fundamental transverse mode oscillation can be maintained up to a high output.

In this embodiment, n-GaAs is used.
A semiconductor laser device may be formed without forming the s-cap layer 19.

A semiconductor laser device according to a second embodiment of the present invention will be described along its manufacturing process, and FIG. 2 is a cross-sectional view of the light emitting surface in the manufacturing process.

As shown in FIG. 2A, n-In _0.49 Ga is formed on an n-GaAs substrate 31 by metal organic chemical vapor deposition.
_0.51 P lower cladding layer 32, n or i-In _x2 Ga
_{1-x2 As 1-y2 P} y2 optical waveguide layer 33 (x2 = (0.49 ± 0.01 ) y2,0
≦ x2 ≦ 0.3), In _x5 Ga _1-x5 As _1-y5 P _y5 (0 ≦ x5 ≦ 0.
3, 0 <y5 ≦ 0.6) tensile strain barrier layer 34, In _x3 Ga
_{1-x3 As 1-y3 P} y3 compressive strain quantum well active layer 35 (0 <x3 ≦ 0.
4,0 ≦ y3 ≦ 0.1), In x5 Ga 1-x5 As 1-y5 P y5 tensile strain barrier layer 36, p or _{i-In x2 Ga 1-x2} As 1-y2
_Py2 upper first optical waveguide layer 37, p-thickness of, for example, 10 nm
In _x6 Ga _1-x6 P first etching stop layer 38 (0.2 ≦ x6 ≦
0.8), n or p-In _x1 G having a thickness of, for example, 10 nm.
a _1-x1 As _1-y1 P _y1 Second etching stopper layer 39 (0 ≦ x1 ≦
0.3, 0 ≦ y1 ≦ 0.6), n-In having a thickness of, for example, 1 μm
_{A 0.49} Ga _0.51 P current confinement layer 40 and an n-GaAs cap layer 41 having a thickness of, for example, 10 nm are laminated. On top of this, SiO
₂ film 42 is formed, and a SiO ₂ film 42 of a stripe region having a width of about 3 μm is formed in the <011> direction by ordinary lithography.
Is removed.

Next, as shown in FIG. 2b, SiO ₂ film 42
As a mask, by etching the GaAs cap layer 41 with a sulfuric acid etchant, it continues to etch the n-In _0.49 Ga _0.51 P current confinement layer 40 in a hydrochloric acid-based _{etchant, In x1 Ga 1-x1 As} 1-y1 P y1 The second etching stop layer 39 is exposed.

Next, as shown in FIG. 2c, SiO ₂ film 42
Is removed with a hydrofluoric acid-based etchant, and then the n-GaAs cap layer 41 and the I on the bottom surface of the groove are removed with a sulfuric acid-based etchant.
n _x1 Ga _1-x1 of As _1-y1 P _y1 second etching stop layer 39 is removed to expose the _{p-In x6 Ga 1-x6} P first etching stop layer 38.

Next, as shown in FIG. 2D, p-In _x2 G
a _1-x2 As _{1-y2 Py} 2 Upper optical waveguide layer 43 (x2 = (0.49 ±
0.01) y2, 0 ≦ x2 ≦ 0.3), p-In _x4 Ga _1-x4 As _1-y4
P _y4 (x4 = (0.49 ± 0.01) y4, 0.9 ≦ y4 ≦ 1) Cladding layer 4
4. A p-GaAs contact layer 45 is formed. A p-side electrode 46 is formed thereon, and the substrate is polished to form an n-side electrode 47. Thereafter, a high-reflectance coat and a low-reflectance coat are applied to the cavity surface formed by cleaving the sample, and thereafter, a semiconductor laser device is formed by chipping.

The thickness of the _{p-In x2 Ga 1-x2} As 1-y2 P y2 first upper optical waveguide layer 37 is the thickness of the fundamental transverse mode oscillation can be maintained up to a high output.

As in the present embodiment, barrier layers may be provided above and below the quantum well active layer. As a result, various characteristics such as a decrease in threshold current can be improved, and reliability can be improved.

Next, a description will be given of a semiconductor laser device according to a third embodiment of the present invention along a manufacturing process thereof, and FIG. 3 is a cross-sectional view along a light emitting direction in the manufacturing process.

As shown in FIG. 3A, n-Al _z1 Ga _1-z1 A is formed on an n-GaAs substrate 51 by metal organic chemical vapor deposition.
s lower cladding layer 52 (0.35 ≦ z1 ≦ 0.7), n or i
-Al _z2 Ga _{1 -z 2} As optical waveguide layer 53 (0 ≦ z2 ≦ 0.2), In
_{x5 Ga 1-x5 As 1-} y5 P y5 (0 ≦ x5 ≦ 0.3,0 <y5 ≦ 0.6) tensile strain barrier layer _{54, In x3 Ga 1-x3} As 1-y3 P y3 compressive strain quantum well active layer 55 ( 0 <x3 ≦ 0.4, 0 ≦ y3 ≦ 0.1), In _{x5
Ga 1-x5 As 1-y5} P y5 tensile strain barrier layer 56, p or _{i-In x2 Ga 1-x2} As 1-y2 P y2 first upper optical waveguide layer 57
(X2 = (0.49 ± 0.01) y2, 0 ≦ x2 ≦ 0.3), the thickness is, for example, 1
P-In _x6 Ga _1-x6 P first etching stopper layer 58 (0.2 ≦ x6 ≦ 0.8) of about 0 nm, and n having a thickness of about 10 nm, for example.
_{Alternatively,} p-In _x1 Ga _1-x1 As _{1-y1 Py 1} second etching stop layer 59 (0 ≦ x1 ≦ 0.3, 0 ≦ y1 ≦ 0.6), for example, having a thickness of 1
An n-In _0.49 Ga _0.51 P current confinement layer 60 having a thickness of μm and an n-GaAs cap layer 61 having a thickness of, for example, 10 nm are laminated.
An SiO ₂ film 62 is formed thereon, and the SiO ₂ film 62 in a stripe region having a width of about 3 μm is removed by ordinary lithography in the <011> direction.

Next, as shown in FIG. 3b, SiO ₂ film 62
As a mask, etching the GaAs cap layer 61 with a sulfuric acid etchant, subsequently, by etching the n-In _0.49 Ga _0.51 P current confinement layer 60 in a hydrochloric acid-based _{etchant, In x1 Ga 1-x1 As} 1-y1 P _y1 The second etching stop layer 59 is exposed.

Next, as shown in FIG. 3c, SiO ₂ film 42
Is removed with a hydrofluoric acid-based etchant, followed by a sulfuric acid-based etchant and the n-GaAs cap layer 61 and the In _x1 Ga _1-x1 As _{1-y1 Py 1} second etching stop layer 59 on the bottom of the groove.
To remove the p-In _x6 Ga _1-x6 P first etching stop layer
Expose 58.

Next, as shown in FIG. 3D, p-In _x2 G
a _1-x2 As _{1-y2 Py} 2 Upper optical waveguide layer 63 (x2 = (0.49 ±
0.01) y2, 0 ≦ x2 ≦ 0.3), p-In _x4 Ga _1-x4 As _1-y4
P _y4 (x4 = (0.49 ± 0.01) y4, 0.9 ≦ y4 ≦ 1) An upper cladding layer 64 and a p-GaAs contact layer 65 are formed. Thereafter, a p-side electrode 66 is formed, and the substrate is polished to form an n-side electrode 67.
To form Thereafter, a high-reflectance coat and a low-reflectance coat are applied to the cavity surface formed by cleaving the sample, and thereafter, a chip is formed to complete a semiconductor laser device. In _x2 Ga
The thickness of the _{1-x2 As 1-y2 P} y2 first upper optical waveguide layer 57 is the thickness of the fundamental transverse mode oscillation can be maintained up to a high output.

Next, a description will be given of a semiconductor laser device according to a fourth embodiment of the present invention along its manufacturing process, and FIG. 4 shows a cross-sectional view in the light emitting direction.

As shown in FIG. 4A, metalorganic vapor phase epitaxy
As a result, n-In is formed on the n-GaAs substrate 71._0.49Ga
_0.51P lower cladding layer 72, n or i-In_x2Ga
_1-x2As _1-y2P_y2Optical waveguide layer 73 (x2 = (0.49 ± 0.01) y2,0
≦ x2 ≦ 0.3), In_x5Ga_1-x5As_1-y5P_y5(0 ≦ x5 ≦ 0.
3, 0 <y5 ≦ 0.6) tensile strain barrier layer 74, In_x3Ga
_1-x3As_1-y3P_y3Compressive strain quantum well active layer 75 (0 <x3 ≦ 0.
4, 0 ≦ y3 ≦ 0.1), In_x5Ga_1-x5As_1-y5P_y5Pull
Strain barrier layer 76 (0 ≦ x5 ≦ 0.3, 0 <y5 ≦ 0.6), p or
Is i-In_x2Ga_1-x2As_1-y2P_y2Upper first optical waveguide layer 77
(X2 = (0.49 ± 0.01) y2, 0 ≦ x2 ≦ 0.3), for example, the thickness is 1
P-In of about 0 nm_x6Ga_1-x6P first etching prevention
Layer 78 (0.2 ≦ x2 ≦ 0.8), n having a thickness of, for example, about 10 nm
Or p-In_x1Ga_1-x1As_1-y1P_y1Second etching
Blocking layer 79 (0 ≦ x1 ≦ 0.3, 0 ≦ y1 ≦ 0.6), for example, having a thickness of 1
μm n-In_0.49Ga_0.51Stack P current confinement layer 80
You. On top of this, SiO_TwoFilm 81 is formed, and <011> direction
A stripe with a width of about 3 μm by ordinary lithography
Region SiO_TwoThe film 81 is removed.

Next, as shown in FIG. 4b, SiO ₂ film 81
N-In _0.49 Ga with hydrochloric acid-based etchant using
An In _x1 by etching a _0.51 P current confinement layer 80
The Ga _1-x1 As _1-y1 P _y1 second etching stopper layer 79 is exposed.

Next, as shown in FIG. 4C, the SiO ₂ film 81 is removed with a hydrofluoric acid-based etchant, and a second etching stop of the In _x1 Ga _1-x1 As _{1-y1 Py1 on} the bottom of the groove is performed with a sulfuric acid-based etchant. Layer 79 is removed, exposing p- _{Inx6Ga1 -x6P} first etch stop layer 78.

Next, as shown in FIG. 4D, p-In _x2 G
a _1-x2 As _{1-y2 Py} 2 Upper optical waveguide layer 82 (x2 = (0.49 ±
0.01) y2, 0 ≦ x2 ≦ 0.3), p-In _x4 Ga _1-x4 As _1-y4
P _y4 (x4 = (0.49 ± 0.01) y4, 0.9 ≦ y4 ≦ 1) An upper cladding layer 83 and a p-GaAs contact layer 84 are formed. A p-side electrode 85 is formed thereon, and the substrate is polished to form an n-side electrode 86. Thereafter, a high-reflectance coat and a low-reflectance coat are applied to the cavity surface formed by cleaving the sample, and then the semiconductor chip is completed by chipping. In _x2 Ga _1-x2
The thickness of the As _{1 -y 2 Py 2} upper first optical waveguide layer 77 is a thickness that can maintain the fundamental transverse mode oscillation up to a high output.

As in the present embodiment, a semiconductor laser device can be manufactured without forming a cap layer.

In the above four embodiments, with respect to the wavelength band λ to oscillate, the compression strain In _x3 Ga _1-x3 As _1-y3
From the _Py3 active layer (0 <x3 ≦ 0.4, 0 ≦ y3 ≦ 0.1), 900 <
Control within the range of λ <1200 (nm) is possible.

Although the above four embodiments only describe a semiconductor laser with a refractive index guiding mechanism, the present invention can also be used for producing a semiconductor laser with a diffraction grating or an optical integrated circuit. It is.

The present invention can be used not only for a semiconductor laser that oscillates in a fundamental transverse mode, but also for a wide stripe laser with a refractive index of 1 μm or more that oscillates in multiple modes. Further, although the layer configuration is described using an n-type GaAs substrate, a p-type conductive substrate may be used, and in this case, all of the above-described conductivity may be reversed.

Further, in the above-described embodiment, a structure called a SQW-SCH having a single quantum well and a constant optical waveguide layer composition has been described. However, a multiple quantum well structure having a plurality of quantum wells instead of the SQW is used. There may be.

As a method for growing the crystal layer, a molecular beam epitaxial growth method using a solid or gas as a raw material may be used.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a step of manufacturing a semiconductor laser device according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a step of manufacturing a semiconductor laser device according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a step of manufacturing a semiconductor laser device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 11,31,51,71 GaAs substrate 13,33,53,73 Lower optical waveguide layer 34,36,54,56,74,76 Tensile strain barrier layer 14,35,55,75 Quantum well active layer 15,37, 57,77 Upper first optical waveguide layer 16,38,58,78 First etch stop layer 17,39,59,79 Second etch stop layer 18,40,60,80 Current confinement layer 19,41,61 Cap layer 21,43,63,82 Upper second optical waveguide layer

Claims (9)

[Claims] 1. A first conductivity type GaAs substrate, a first conductivity type cladding layer, a lower optical waveguide layer, and In _x3 Ga having a composition ratio of 0 <x3 ≦ 0.4 and 0 ≦ y3 ≦ 0.1.
_{1-x3 As 1-y3 P} y3 compressive strain quantum well active layer, the composition ratio is x2 = (0.49 ± 0.01) y2, and 0 ≦ x2 ≦ 0.3 I
_{n x2 Ga 1-x2 As 1} -y2 P y2 first upper optical waveguide layer, the second conductivity type composition ratio is _{0.2 ≦ x6 ≦ 0.8 In x6 Ga} 1-x6
P x first etching stopper layer, In _x1 Ga having a composition ratio of 0 ≦ x1 ≦ 0.3 and 0 ≦ y1 ≦ 0.6 from which a striped portion serving as a current injection window has been removed.
_1-x1 As _{1-y1 Py1} Second etching stop layer, the first conductivity type In _0.49 Ga _0.51 P current confinement layer from which the striped portion serving as the current injection window has been removed is the crystal layer formed in this order. Above, a second conductivity type In _x2 Ga _1-x2 As _{1-y2 Py} 2 upper second optical waveguide layer having a composition ratio of x2 = (0.49 ± 0.01) y2 and 0 ≦ x2 ≦ 0.3, and a composition ratio of x4 = (0.49 ± 0.01) a second conductivity type In _x4 Ga _1-x4 As _{1-y4 Py 4} clad layer _satisfying y4 and 0.9 ≦ y4 ≦ 1, and a second conductivity type contact layer are formed in this order, and the compression strain The absolute value of the product of the strain amount and the film thickness of the quantum well active layer is 0.25 nm or less; the product of the strain amount and the film thickness of the first etching stop layer; An absolute value of a sum of thickness products is equal to or less than 0.25 nm; and the compression-strained quantum well active layer, the first etching stopper layer, and the second etching stopper. A semiconductor laser device in which all layers except the stop layer have a composition that lattice-matches with the first conductivity type GaAs substrate. 2. _Inx5 Ga having a composition ratio of 0 ≦ x5 ≦ 0.3 and 0 <y5 ≦ 0.6 above and below the compression-strained quantum well active layer.
_{1-x5 As 1-y5 P} y5 tensile strain barrier layer is formed, the product of the strain amount and the film thickness of the compressive strain quantum well active layer, the strain amount of the cited tension strain barrier layer and the two tensile strain 2. The semiconductor laser device according to claim 1, wherein the absolute value of the sum of the products of the total film thickness of the barrier layers is 0.25 nm or less. 3. The semiconductor laser according to claim 1, wherein said In _x1 Ga _1-x1 As _{1-y1 Py1} second etching stop layer is of a first conductivity type or a second conductivity type. apparatus. 4. The semiconductor laser device according to claim 1, wherein the width of the stripe is 1 μm or more. 5. The method according to claim 1, wherein the compression-strain quantum well active layer is composed of a plurality of quantum wells.
5. The semiconductor laser device according to 2, 3, or 4. 6. A first-conductivity-type GaAs substrate, a first-conductivity-type cladding layer, a lower optical waveguide layer, and In _x3 Ga having a composition ratio of 0 <x3 ≦ 0.4 and 0 ≦ y3 ≦ 0.1.
_{1-x3 As 1-y3 P} y3 compressive strain quantum well active layer, the composition ratio is x2 = (0.49 ± 0.01) y2, and 0 ≦ x2 ≦ 0.3 I
_{n x2 Ga 1-x2 As 1} -y2 P y2 first upper optical waveguide layer, the second conductivity type composition ratio is _{0.2 ≦ x6 ≦ 0.8 In x6 Ga} 1-x6
P first etching stop layer, In _x1 Ga whose composition ratio is 0 ≦ x1 ≦ 0.3 and 0 ≦ y1 ≦ 0.6
_1-x1 As _{1-y1 Py 1} second etching stop layer, first conductivity type In _0.49 Ga _0.51 P current confinement layer, and GaAs cap layer are laminated in this order, the first conductivity type GaAs cap layer and the first conductivity type. The striped portion serving as the current injection window of the type In _0.49 Ga _0.51 P current confinement layer is removed, and the striped portion serving as the current injection window is removed.
After simultaneously removing the stripe-shaped portion serving as the current injection window of the aAs cap layer and the second etching stop layer, the first conductivity type In _0.49 Ga _0.51 P
The composition ratio is x2 = (0.49
± 0.01) y2 and the second conductivity type In _x2 G satisfying 0 ≦ x2 ≦ 0.3
a _1-x2 As _{1-y2 Py} 2 upper second optical waveguide layer, second conductivity type In _x4 Ga _1-x4 As _1-y4 whose composition ratio is x4 = (0.49 ± 0.01) y4 and 0.9 ≦ y4 ≦ 1 A _Py4 cladding layer and a second conductivity type contact layer are stacked in this order, the absolute value of the product of the strain amount and the film thickness of the compression-strained quantum well active layer is set to 0.25 nm or less, and the strain of the first etching stop layer is reduced. The absolute value of the sum of the product of the amount and the film thickness and the product of the strain amount and the film thickness of the second etching stop layer is 0.25 nm or less, and the compressive strain quantum well active layer, the first etching stop layer, and the A method of manufacturing a semiconductor laser device, wherein all layers except the second etching stop layer are lattice-matched with the GaAs substrate of the first conductivity type. 7. The semiconductor laser device according to claim 6, wherein the In _x1 Ga _1-x1 As _{1-y1 Py1} second etching stop layer is of a first conductivity type or a second conductivity type. Production method. 8. The method according to claim 6, wherein said GaAs cap layer is of a first conductivity type or a second conductivity type. 9. In _x5 Ga having a composition ratio of 0 ≦ x5 ≦ 0.3 and 0 <y5 ≦ 0.6 above and below the compression-strained quantum well active layer.
_1-x5 As _1-y5 laminating P _y5 tensile strain barrier layer, the strain in the compressive strain quantum well active layer and the product of the film thickness, the strain amount of the cited tension strain barrier layer and the two tensile strain barrier layer 9. The method of manufacturing a semiconductor laser device according to claim 6, wherein the absolute value of the sum of the products of the total film thicknesses is set to 0.25 nm or less.