JPH06112580A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To stabilize the oscillation wavelength of a semiconductor device used as a light source for optical information processing, etc., so as to lower the operating current value of the device. CONSTITUTION:A first Ga1-y1Aly1As light guide layer 5 of one conductivity and second Ga1-y2Aly2As light guide layer 6 having a diffraction grating are formed at least one of the main surfaces of a Ga1-xAlxAs active layer 4 and a Ga1-zAlzAs current blocking layer 7 of the other conductivity having a stripe- like window 7a is formed on the layer 6. Then a Ga1-y3Aly3As clad layer 9 of the same conductivity as that of the layer 5 is formed in the window 7a and, at the same time, relations Z>Y3>Y2>X>=0 and Y1>Y2 are established among the X, Y1, Y2, Y3, and Z deciding the AlAs mixed crystal ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed feedback type or distributed reflection type semiconductor laser, which has a wavelength in the visible range and has a stable oscillation wavelength in a wide temperature range and a low operating current, which is suitable as a light source for optical information processing. -Regarding the device.

[0002]

2. Description of the Related Art A conventional semiconductor laser device will be described below. FIG. 9 is a perspective view of a main part of a conventional distributed feedback semiconductor laser device (Proceedings of the Spring Applied Physics Society of Japan 1988 Proceedings 28a-ZP-3 or IEEE Journal of Quantum).
Electron. Vol.25 p.1489 (1989)). An n-type GaAs current blocking layer 22 having a window 22a serving as a current channel on a p-type gallium arsenide (GaAs) substrate 21.
Is formed on the p-type gallium aluminum arsenide (Ga _0.5 Al _0.5 As) clad layer 23, and p-type Ga
_0.87 Al _0.13 As active layer 24, n-type Ga _0.5 Al _0.5 A
n-type Ga having s barrier layer 25 and diffraction grating 26a
_0.75 Al _0.25 As Optical guide layer 26, n-type Ga _0.25 Al
_{A 0.75} As clad layer 27 and an n-type GaAs contact layer 28 are formed.

In the structure of FIG. 9, the current injected from the p-type GaAs substrate 21 is effectively confined in the window 22a, and laser oscillation occurs in the active layer 24 above the window 22a. At this time, since the band gap of the GaAs current block layer 22 is smaller than the energy of the wavelength of the laser light, the laser light is absorbed by the current block layer 22 in the region other than the window 22a, so that the laser light is also effectively contained in the window 22a. It is confined and a single transverse mode lasing is obtained. In this way, the laser oscillates in the distributed feedback (hereinafter abbreviated as DFB) mode by the diffraction grating 26a existing on the optical guide layer 26, so that a wavelength stable laser light source with no mode hop in a wide temperature range can be obtained.

[0004]

However, the above-mentioned conventional structure has a problem that the threshold value and the efficiency are limited by the absorption of the laser light by the GaAs current blocking layer, resulting in a high operating current value. Was there.

That is, an increase in the operating current value causes heat generation in the element, especially at high output, and lengthens the gain distribution. At this time, the semiconductor laser deviates from the oscillation in the DFB mode having a wavelength determined by the diffraction grating and oscillates in the Fabry-Perot (hereinafter abbreviated as FP) mode, so that the oscillation wavelength becomes unstable at high output.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a semiconductor laser device having a low operating current.

[0007]

In order to achieve this object, the semiconductor laser device of the present invention has a Ga ₁ -Y _{1 1} conductivity type Ga ₁ -Y ₁ on at least one side of the main surface of the Ga _{1 -X} Al _X As active layer. A
l _Y1 As Ga having a first light guide layer and a diffraction grating
_1-Y2 Al _Y2 As A second optical guide layer is formed,
A reverse conductivity type Ga ₁ -Z Al _Z As current blocking layer having a stripe-shaped window is formed on the light guide layer, and the reverse conductivity type Ga _{1 -Y 3} Al _Y3 As layer is formed in the stripe-shaped window. Are formed, and X, Y that determine the AlAs mixed crystal ratio
Z>Y3>Y2> X ≧ between 1, Y2, Y3 and Z
0, Y1> Y2.

[0008]

With this structure, the laser light is confined in the stripe due to the existence of the Ga _{1 -Z} Al _Z As current blocking layer having a higher mixed crystal ratio than the Ga _{1 -Y 3} Al _{Y 3} As layer. At this time, since the current blocking layer is transparent to the laser light, the laser light is not absorbed. Furthermore, the presence of the diffraction grating stabilizes the wavelength over a wide temperature range and fluctuations in the light output.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a main part of a semiconductor laser device according to a first embodiment of the present invention. n-type GaA
An n-type GaAs buffer layer 2 is formed on an s substrate 1, and an n-type Ga _0.5 Al _0.5 As clad layer 3, a Ga _0.85 Al _0.15 As active layer 4, and a p-type Ga _0.5 are formed on the n-type GaAs buffer layer 2.
An Al _0.5 As first light guide layer 5 and a p-type Ga _0.8 Al _0.2 As second light guide layer 6 having a diffraction grating 6a in the cavity direction are formed. The period of the diffraction grating is a period that is an integral multiple of the wavelength in the medium. Further, in order to enhance the wavelength selectivity, the period at the center of the diffraction grating is set to 1/4 of the wavelength in the medium.
You may just shift. On the diffraction grating 6a, there is a window 7a which serves as a current channel due to current constriction.
A Ga _0.4 Al _0.6 As current blocking layer 7 of p-type is formed, and a Ga _0.5 Al _0.5 As clad layer 9 of p-type is formed on the window 7a. 8 Ga _0.8 Al _{0 .2} As protective layer, 10 is a p-type GaAs contact layer.

Here, in order to obtain stable single transverse mode oscillation, the AlAs mixed crystal ratio of the current block layer 7 is set to p-type Ga.
_{It is} set higher than the AlAs mixed crystal ratio of _0.5 Al _0.5 As clad layer 9. If the AlAs mixed crystal ratio of the current blocking layer 7 is about the same as that of the cladding layer 9, there is a decrease in the refractive index in the stripe due to the plasma effect, the waveguide serves as an antiguide, and a single transverse mode oscillation cannot be obtained. When the AlAs mixed crystal ratio of the current blocking layer 7 is lower than that of the p-type Ga _0.5 Al _0.5 As cladding layer 9, the transverse mode becomes completely unstable. In this embodiment, as shown in FIG. 1, the current blocking layer 7
The AlAs mixed crystal ratio is set to 0.6, which is 0.1 higher than the AlAs mixed crystal ratio of the p-type Ga _0.5 Al _0.5 As clad layer 9.

In this structure, a p-type GaAs contour is used.
The current injected from the insulating layer 10 is trapped in the window 7a.
Ga at the bottom of the window 7a_0.85Al_0.157 in As active layer 4
Laser oscillation in the 80 nm band occurs. Here, p-type Ga
_0.5Al_0.5Activate the AlAs mixed crystal ratio of the As first optical guide layer 5.
Is sufficiently higher than the AlAs mixed crystal ratio of the functional layer 4,
Carriers are effectively confined in layer 4 and oscillation in the visible range is possible
I am trying. In order to obtain laser oscillation in the 780 nm band
Requires an AlAs mixed crystal ratio of 0.45 or more,
In this embodiment, it is set to 0.5. The re-growth of AlAs mixed crystal ratio
Low p-type Ga _0.8Al_0.2As 2nd light guide layer 6 top
Therefore, there is no problem of surface oxidation. Again
2 As the AlAs mixed crystal ratio of the optical guide layer 6, regrowth is acceptable.
It is easily less than 0.3 and is transparent to the oscillation wavelength of the laser.
It is desirable that the value is 0.2 in this embodiment. It
In addition, the film thickness does not affect the light distribution so much 0.0
5 μm or less is desirable, and in this embodiment, 0.03 μm
ing. As described above, in this embodiment, the carriers are confined.
The layer (first light guide layer 5) and the layer to be regrown (second light guide layer 5).
By forming the id layer 6) separately, the emission in the visible range
It is possible to shake. In addition, n-type Ga_0.4Al_0.6
The forbidden band width of the As current blocking layer 7 is Ga_0.85Al_0.15A
Since it is larger than the forbidden band width of the active layer 4, the current block
Low operation with no waveguide absorption and no light absorption by layer 7
An element of current is obtained.

In the structure of this embodiment, the refractive index in the medium changes periodically due to the existence of the diffraction grating 6a, and the light traveling parallel to the cavity direction is reflected periodically. The diffraction grating 6a has a period that is an integral multiple of the wavelength in the medium,
Since the light reflected by the diffraction grating 6a has the same phase, the wavelength selectivity becomes strong. Therefore, single longitudinal mode oscillation can be maintained against temperature changes, changes in optical output, high-speed modulation, and the like.

2A to 2C are manufacturing process diagrams of a semiconductor laser device in one embodiment of the present invention. First, Figure 2
As shown in (a), MO is formed on the n-type GaAs substrate 1.
The n-type GaAs buffer layer 2, the n-type Ga _0.5 Al _0.5 As clad layer 3, G are formed by the CVD method or the MBE growth method.
a _0.85 Al _0.15 As active layer 4, p-type Ga _0.5 Al _{0. 5} A
The s first light guide layer 5 and the p-type Ga _0.8 Al _0.2 As second light guide layer 6 are grown. Next, a diffraction grating is patterned on the resist film by a two-beam interference exposure method using a He-Cd laser as a light source, and the diffraction grating 6a is etched.
To form.

Next, as shown in FIG. 2B, n-type Ga
_0.4 Al _0.6 As current blocking layer 7 and Ga _0.8 Al _0.2
The As protective layer 8 is grown again by the MOCVD method or the MBE growth method, and the stripe-shaped window 7a is formed by photoetching. As an etching method, first, the Ga _0.4 Al _0.6 As current blocking layer 7 is etched to an intermediate point with an etchant such as tartaric acid or sulfuric acid having a low selectivity with respect to the AlAs mixed crystal ratio, and then hydrofluoric acid-based or phosphoric acid-based. Ga _0.4 Al _0.6 is selectively formed by using an etchant capable of selectively etching a layer having a high AlAs mixed crystal ratio such as a system.
The As current blocking layer 7 is etched. P-type G
Since the a _0.8 Al _0.2 As second optical guide layer 6 also functions as an etching stop layer, variations due to etching are small and a high yield can be obtained. The stripe width at this time was 2 μm. The stripe shape is preferably a forward mesa shape rather than an inverted mesa shape. That is, when the inverted mesa shape is formed, crystal growth is more difficult than in the case where the forward mesa shape is formed, and the yield may be reduced due to the deterioration of the characteristics. In fact, in the case of the inverted mesa shape, the crystallinity of GaAlAs grown on the side surface portion of the window 7a was impaired, and the threshold current of the manufactured element was about 10 mA higher than that of the element of the forward mesa shape. The characteristics of the element to be described later show a forward mesa shape. Protective layer 8 is required to protect the top of the n-type Ga _{0. 4} Al _0.6 As current blocking layer 7 from the surface oxidation. In addition, AlA of the protective layer 8
As with the second optical guide layer, the s mixed crystal ratio is preferably 0.3 or less, which facilitates re-growth, and a mixed crystal ratio which is transparent to laser light.

Next, as shown in FIG. 2C, MOCVD is performed.
Method or p-type Ga _0.5 Al _0.5 As by MBE growth method
The clad layer 9 and the p-type contact layer 10 are formed by regrowth. At this time, A is in the stripe where current flows.
Since the growth is on the p-type Ga _0.8 Al _0.2 As second optical guide layer 6 having a low 1As mixed crystal ratio, the growth can be easily performed.
However, when Zn is used as a dopant for the p-type Ga _0.5 Al _0.5 As cladding layer 9, diffusion of Zn into the stripe region during regrowth affects the characteristics,
The carrier concentration is at least 10 ¹⁸ c at the regrowth interface.
It must be less than m ^-3 . In this embodiment, 7 × 10 ¹⁷ c
m ^-3 . There is also a method of using a dopant such as carbon, which does not diffuse much, instead of Zn. Finally, n-type G
aAs substrate 1 side and p-type GaAs contact layer 10
An electrode is formed on each side.

2A to 2C, the conductivity types of the active layer 4 and the protective layer 8 are not particularly described, but they may be p-type or n-type, or may be non-doped. I don't mind. Further, the film thickness of the current block layer 7 needs to be at least 0.4 μm because the laser beam is absorbed in the upper p-type GaAs contact layer 10 when the current block layer 7 is thin.

In this embodiment, the diffraction grating formed on the p-type Ga _0.8 Al _0.2 As second optical guide layer 6 was taken up, but it is on the Ga _0.8 Al _0.2 As protective layer 8 or active. It may be formed under the layer 4.

FIG. 3 is a perspective view of a main portion of a semiconductor laser device according to the second embodiment of the present invention. As shown in FIG.
In this embodiment, the diffraction grating 8a is formed on the Ga _0.8 Al _0.2 As protective layer 8. Manufacturing method of this structure, grown up Ga _{0. 8} Al _0.2 As protective layer 8 by first growing, forming a diffraction grating 8a thereon. Next, a window 7a serving as a current channel is formed in the current blocking layer 7 and the protective layer 8 by etching, and then p-type Ga _0.5
Al _0.5 As clad layer 9 and p-type GaAs layer 10
To grow.

FIG. 4 is a perspective view of the essential portions of a semiconductor laser device according to the third embodiment of the present invention. As shown in FIG.
In this embodiment, the diffraction grating 11a is formed under the active layer 4. Manufacturing method of this structure, n-type Ga _0.8
After growing up to Al _0.2 As third optical guide layer 11, a diffraction grating 11a is formed, and after growing up to p-type Ga _0.8 Al _0.2 As protective layer 8, a window 7a to be a current channel is formed. P-type Ga _0.5 Al _0.5 As clad layer 9
Then, the p-type GaAs layer 10 is grown.

The second light guide near at least one of the end faces.
Distributed reflection with a diffraction grating formed in the cavity direction on the id layer
Type laser (hereinafter abbreviated as DBR)
Is obtained. FIG. 5 shows a semiconductor device according to the fourth embodiment of the present invention.
FIG. 3 is a perspective view of a main part of a body laser device, which is a DBR laser.
The case is shown. Manufacturing method in this structure
Is Ga _0.8Al_0.2Crystal growth up to As protective layer 8 once
And etching the window 7a, and then p-type Ga_0.5
Al_0.5As clad layer 9 and p-type GaAs layer 10
, And finally, the end face is p-type Ga_0.8Al_0.2As
Etching until layer 6 is exposed to form diffraction grating 6a
To do. The etching at this time is the etching of the stripe part.
The selective etching method used for the etching is used. DBR
The laser diffracts the laser light depending on the period of the diffraction grating.
It is also possible to take it out in a direction perpendicular to the child,
A vertical surface emitting laser can be realized.

FIG. 6 is a diagram showing the current-light output characteristics of the semiconductor laser device in one embodiment of the present invention. Since there is no light absorption in the current blocking layer 7 as compared with the conventional example, a lower operating current can be realized. For example, the resonator length is 250 μm, 15
% / 75% on the element with 100% coating
A light output of W or more is obtained. The transverse mode also oscillates in a stable fundamental mode up to high output.

FIG. 7 is a diagram showing the optical output dependence of the oscillation wavelength of the semiconductor laser device in one embodiment of the present invention. Conventionally, at 50 mW or more, heat generation of the element causes a mode hop to the wavelength of the Fabry-Perot mode, which causes fluctuation of the wavelength, whereas the structure of the present invention is stable up to 100 mW.
A mode oscillation was obtained.

FIG. 8 is a diagram showing the temperature dependence of the oscillation wavelength of the semiconductor laser device in one embodiment of the present invention. With the structure of the present invention, stable laser oscillation without mode hop can be obtained up to 80 ° C. at a high output of 50 mW, and excellent characteristics are obtained especially at high temperature operation as compared with the conventional example.

Since the threshold value can be reduced by forming the active layer 4 into a quantum well structure, a low operating current and a high output can be achieved, and the characteristics shown in FIGS. 6 to 8 can be further improved. it can. 780n as a quantum well structure
Ga _0.95 Al _0.05 A with a thickness of 10 nm that oscillates in the m band
4 s-well layers and 4 nm thick Ga _0.7 Al _0.3 As
Multi-quantum well (MQ consisting of 5 barrier layers)
When the W) structure was used, a light output of 200 mW or more was obtained. Still other quantum well structures, namely, single quantum well (SQW) structure, double quantum well (DQ) structure
The same applies to a W) structure, a triple quantum well (TQW) structure, a grin (GRIN) structure or a separate confinement heterostructure (SCH) structure thereof.

It should be noted that in all the above-mentioned embodiments, n-type Ga is used.
Although the case where the As substrate 1 and the n-type current blocking layer 7 are used has been described, the p-type GaAs substrate 1 may be p-type and the p-type current blocking layer may be used. That is, this is because the AlAs mixed crystal ratio of the current block layer 7 is high, and in the case of the p-type GaAlAs layer having a high AlAs mixed crystal ratio, the diffusion of electrons is suppressed, so that the p-type block layer can be realized. is there.

[0026]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the active layer G
a _1-X Al X As layer Ga _1-Y2 Al _Y2 As the second light guide layer having one conductivity type Ga _1-Y1 Al _Y1 As the first light guide layer and a diffraction grating on at least one side of the main surface of the And a reverse conductivity type Ga ₁ -Z Al _Z As current blocking layer having a stripe-shaped window is formed on the second optical guide layer, and the stripe-shaped window has one conductivity-type Ga. _1-Y3 Al
_{A Y3} As layer is formed, and Z>Y3>Y2> is present between X, Y1, Y2, Y3 and Z that determine the AlAs mixed crystal ratio.
With the configuration in which the relationship of X ≧ 0, Y1> Y2 is established, it is possible to easily realize a semiconductor laser device having a stable oscillation wavelength against a temperature change, a change in optical output, etc. and an excellent low operating current. is there.

Further, in the semiconductor laser of the present invention, the AlAs mixed crystal ratio of the current block layer is set higher than the AlAs mixed crystal ratio of the cladding layer, so that the semiconductor laser oscillates in the single transverse mode, and the laser light is blocked by the current block layer. Since there is no light absorption, a low operating current value can be obtained. Further, by forming a diffraction grating, it is possible to oscillate in a wavelength stable DFB mode. By lowering the operating current, the amount of heat generated by the device can be reduced at high output, so that mode hop to Fabry-Perot mode can be suppressed and a semiconductor laser with a stable oscillation wavelength up to high output can be obtained.

Furthermore, since the heat generation amount of the laser mount can be reduced by lowering the operating current, it is possible to use a small and lightweight heat sink, and it is possible to realize the resin package of the laser package, which was conventionally a metal, and to greatly improve the pickup. Miniaturization and cost reduction can be achieved.

By using the semiconductor laser device having the above-mentioned effects in the field of optical information processing, a great effect is achieved in miniaturization and high performance of optical information processing equipment.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a semiconductor laser device according to a first embodiment of the present invention.

2A to 2C are manufacturing process diagrams of a semiconductor laser device according to an embodiment of the present invention.

FIG. 3 is a perspective view of a main part of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a main part of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 5 is a perspective view of an essential part of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing current-light output characteristics of a semiconductor laser device according to an embodiment of the present invention.

FIG. 7 is a diagram showing the optical output dependence of the oscillation wavelength of the semiconductor laser device in one embodiment of the present invention.

FIG. 8 is a diagram showing temperature dependence of an oscillation wavelength of a semiconductor laser device according to an embodiment of the present invention.

FIG. 9 is a perspective view of a main part of a conventional semiconductor laser device.

[Explanation of symbols]

4 Ga _0.85 Al _0.15 As active layer (Ga _1-X Al _X As active layer) 5 Ga _0.5 Al _0.5 As First optical guide layer (Ga _{1-Y 1} Al)
_Y1 As first light guide layer) 6 Ga _0.8 Al _0.2 As second light guide layer (Ga _{1 -Y2} Al
_Y2 As second optical guide layer) 7 Ga _0.4 Al _0.6 As current blocking layer (Ga _{1 -Z} Al _Z
As current blocking layer) 7a Striped window 9 Ga _0.5 Al _0.5 As clad layer (Ga _{1 -Y 3} Al _{Y 3} A
s clad layer)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Ito 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd.

Claims (8)

[Claims] 1. A Ga ₁ -Y ₁ Al _Y1 As first optical guide layer of one conductivity type and a Ga _{1 -Y2} Al _Y2 having a diffraction grating on at least one side of the main surface of the Ga _{1 -X} Al _x As active layer. As second
An optical guide layer is formed, and Ga ₁ -Z Al _Z As of the reverse conductivity type having a striped window on the second optical guide layer is formed.
A current blocking layer is formed, a Ga _{1 -Y 3} Al _{Y 3} As layer of one conductivity type is formed in the stripe-shaped window, and X, Y 1, Y 2, Y 3 which determine the AlAs mixed crystal ratio.
And Z are semiconductor laser devices having a relationship of Z>Y3>Y2> X ≧ 0, Y1> Y2. Wherein Ga _1-X Al X As the one conductivity type on at least one side of the main surface of the active layer Ga _1-Y1 Al _Y1 As the first light guide layer and Ga _1-Y2 Al _Y2 As the second light A guide layer is formed, a reverse conductivity type Ga ₁ -Z Al _Z As current block layer having a stripe-shaped window is formed on the second optical guide layer, and diffraction is formed on the current block layer. A GaAlAs layer having a lattice is formed, a Ga ₁ -Y ₃ Al _{Y 3} As layer of one conductivity type is formed in the stripe-shaped window, and X, Y 1, Y for determining the AlAs mixed crystal ratio.
2, Y3 and Z between Z>Y3>Y2> X ≧ 0, Y1
A semiconductor laser device having a relation of> Y2. 3. One conductivity type GaAlA having a diffraction grating
A GaAlAs clad layer of one conductivity type is formed on the s layer, and a Ga _1-X Al _X As active layer, a Ga _{1-Y 1} Al _{Y 1} As first optical guide layer of the opposite conductivity type, and a Ga _{1- Y2} Al
_Y2 As second light guide layer is formed, and Ga of one conductivity type having a striped window on the second light guide layer
_{A 1-Z} Al _Z As current block layer is formed, a Ga ₁ -Y ₃ Al _{Y 3} As layer of opposite conductivity type is formed in the stripe-shaped window, and X, Y that determine the AlAs mixed crystal ratio.
Z>Y3>Y2> X ≧ between 1, Y2, Y3 and Z
A semiconductor laser device having a relationship of 0, Y1> Y2. 4. A Ga ₁ -Y ₁ Al _{Y 1} As first optical guide layer of one conductivity type and a Ga _{1 -Y 2} Al _{Y 2} As second layer having one conductivity type Ga ₁ -Y ₁ Al _{Y 1} As on at least one side of the main surface of the active layer of the quantum well structure. A light guide layer is formed, and a Ga ₁ -Z Al _Z As current blocking layer of the opposite conductivity type having a stripe-shaped window is formed on the second light guide layer, and the stripe-shaped window is formed in the stripe-shaped window. A semiconductor layer in which a Ga _{1 -Y 3} Al _Y3 As layer of one conductivity type is formed and which has a relationship of Z>Y3> Y2, Y1> Y2 between Y1, Y2, Y3 and Z that determine the AlAs mixed crystal ratio. -The device. 5. A quantum well structure active layer at least one of the 1 second Ga _1-Y1 Al _Y1 As the one conductivity type on the side of light of the main surface guides of layers and Ga _1-Y2 Al _Y2 As the second light guide layer A reverse conductivity type Ga ₁ -Z Al _Z As current block layer having a stripe-shaped window is formed on the second light guide layer, and a diffraction grating is formed on the current block layer. GaAlAs layer is formed, said stripe-shaped window are Ga _1-Y3 Al _Y3 As layer of the one conductivity type is formed, and determines the AlAs mixed crystal ratio Y1, Y2, Y3
And Z have a relationship of Z>Y3> Y2, Y1> Y2. 6. One conductivity type GaAlA having a diffraction grating
There is a GaAlAs cladding layer of one conductivity type on the s layer.
On top of which is an active layer of quantum well structure and Ga of opposite conductivity type. _1-Y1Al
_Y1As first light guide layer and Ga_1-Y2Al_Y2As second light
A guide layer is formed on the second optical guide layer.
One conductivity type Ga having a tripe-shaped window _1-ZAl_ZAs Den
Flow blocking layer is formed, and the striped window is formed.
Reverse conductivity type Ga_1-Y3Al_Y3As layer is formed
And Y1, Y2, Y3 and Y3 which determine the AlAs mixed crystal ratio
And Z have a relationship of Z> Y3> Y2 and Y1> Y2.
Semiconductor laser device. 7. Ga _1-X Al X As the one conductivity type on the active layer Ga _1-Y1 Al _Y1 As the first light guide layer and Ga _1-Y2 A
l _Y2 As second light guide layer is formed, a diffraction grating is formed on the second light guide layer at least near one end face, and a second light guide layer in which the diffraction grating is not formed is formed. Ga of the opposite conductivity type having a striped window on top
_{A 1-Z} Al _Z As current blocking layer is formed, a Ga ₁ -Y ₃ Al _{Y 3} As layer of one conductivity type is formed in the striped window, and X, Y that determine the AlAs mixed crystal ratio.
Z>Y3>Y2> X ≧ between 1, Y2, Y3 and Z
A semiconductor laser device having a relationship of 0, Y1> Y2. 8. Ga _1-Y1 Al _Y1 As the first light guide layer of one conductivity type on the active layer of a quantum well structure and Ga _1-Y2 Al
_{A Y2} As second light guide layer is formed, a diffraction grating is formed on at least one end face of the second light guide layer, and a diffraction grating is not formed on the second light guide layer. Has Ga of the opposite conductivity type with a striped window
_{A 1-Z} Al _Z As current blocking layer is formed, a Ga ₁ -Y ₃ Al _{Y 3} As layer of one conductivity type is formed in the striped window, and Y 1 and Y that determine the AlAs mixed crystal ratio are formed.
A semiconductor laser device having a relationship of Z>Y3> Y2, Y1> Y2 between 2, Y3 and Z.