JPH0846281A - Semiconductor laser device - Google Patents

Abstract

(57) [Summary] [Object] To provide a semiconductor laser device having an internal stripe structure, which has a stable transverse mode, a small reactive current, and a low operating voltage. [Structure] A stripe-shaped groove 2 having at least a (111) plane is formed on a (100) plane of a p-type GaAs substrate 1, and N-doped Zn _y Mg _1-y S _z Se is formed on the substrate in this state.
_1-z (0 ≦ y ≦ 1, 0 ≦ z ≦ 1) layers are stacked.
Furthermore, a p-type clad layer 5, an active layer 7 and an n-type clad layer 9 made of a II-VI group compound semiconductor are formed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to II-V on a GaAs substrate.
The present invention relates to a blue to blue-green semiconductor laser device composed of a group I compound semiconductor, and particularly to a semiconductor laser device having an internal stripe structure.

[0002]

2. Description of the Related Art In recent years, many blue to blue-green semiconductor laser devices composed of II-VI group compound semiconductors have been reported to perform laser oscillation by current injection (for example, ELECTRONICS LETTERS 2).
9 (9), 766 ('93)). All of the structures of the semiconductor laser devices used in these reports are so-called electrode stripe structures.

FIG. 6 shows a sectional view of a conventional semiconductor laser device having an electrode stripe structure. This semiconductor laser device is formed on an n-type GaAs substrate 101 having a (100) plane, and n-type Zn _y Mg _1-y S _z is formed on the substrate 101.
Se _1-z (y = 0.9, z = 0.1) cladding layer 10
2, n-type ZnS _z Se _1-z (z = 0.06) guide layer 10
3, Zn _x Cd _1-x Se (x = 0.8) active layer 104, p
Type ZnS _z Se _1-z (z = 0.06) guide layer 105, p
Type Zn _y Mg _1-y S _z Se _1-z (y = 0.9, z = 0.1)
A dielectric insulating film 108 made of, for example, a SiN film having a clad layer 106, a p-type ZnSe contact layer 107, and a stripe portion 109 is laminated in this order from the substrate 101 side. Further, a p-type electrode 110 made of, for example, Au is provided on the dielectric insulating film 108 side with the laminated body sandwiched therebetween.
However, an n-type electrode 111 made of a similar material is formed on the substrate 101 side.
Are formed. Here, regarding the conductivity type, one having holes as majority carriers is called p-type, and one having electrons as majority carriers is called n-type.

In this semiconductor laser device, by applying a voltage between electrodes 110 and 111, a current is caused to flow only through stripe portion 109 to inject electrons from n-type cladding layer 102 and n-type guide layer 103 into active layer 104. Then
Holes are injected from the p-type guide layer 105 and the p-type cladding layer 106. The electrons and holes injected into the active layer 104 recombine to radiate light, but when the injected current level increases, stimulated emission starts and laser oscillation occurs. The laser light is guided by a gain waveguide mode in which the optical gain is large only under the stripe portion 109 in the active layer 104.

By the way, N-doped Zn _y Mg _1-y S
_{In z} Se _1-z (0 ≦ y ≦ 1 and 0 ≦ z ≦ 1), the doping efficiency changes depending on the plane orientation of the GaAs substrate used for epitaxial growth. For example, (3
In the case of growing on a higher-order surface such as 11), (511), or (711), the doping efficiency is improved as compared with the case of growing on the (100) surface. This improvement in doping efficiency increases the p-type carrier concentration. In addition, (1
11) When grown on the surface, the doping efficiency decreases. It is known that due to this decrease in doping efficiency, high resistance is exhibited. These characteristics are observed on both A-plane and B-plane. Among these characteristics, as an example of improving the laser characteristics by utilizing the increase of the carrier concentration due to the growth on the higher order surface,
A blue to blue-green semiconductor laser device having an electrode stripe structure as described above, which is composed of a II-VI group compound semiconductor on a GaAs substrate having a (311) A plane, is known (1993 International).
Conference on Solid State
Devices and Materials, LC-
11, pp. 976-977).

[0006]

The semiconductor laser device shown in FIG. 6 described above has the following problems. First, when the drive current is increased, the carriers injected into the active layer 104 gradually spread from directly under the stripe portion 109 to both sides, so that the high gain region spreads and the lateral mode spreads. Further, since carriers are injected into the region directly below the stripe portion 109, the refractive index in this region is smaller than the refractive index in the region where carriers are not injected. For this reason, it becomes impossible to confine light with the actual refractive index difference and guide the light, and the lateral modes are spread and high-order lateral mode oscillation is caused, and the lateral modes become unstable. When the transverse mode is unstable in this way, a kink occurs in the current-optical output characteristic. In addition, when this semiconductor laser device is used for a magneto-optical disk, laser light cannot be focused well, so that there is a problem that data writing to the disk and data reading from the disk cannot be performed.

A part of the current injected from the stripe portion 109 spreads laterally in the guide layer 105, the cladding layer 106 and the contact layer 107. For this reason, there is a problem that the current injected from directly below the stripe portion 109 and laterally spread cannot contribute to the gain of the laser light, and becomes a reactive current, resulting in an increase in operating current.

Further, in the II-VI group compound semiconductor,
Generally, when the conductivity type is p-type, the carrier concentration of holes, which are majority carriers, cannot be increased. For example, when grown on the (100) plane of a substrate,
The carrier concentration rises to about 1 × 10 ¹⁸ cm ^-3 at most. For this reason, the electric resistance of the semiconductor laser device increases, which causes an increase in operating voltage, and a large amount of Joule heat is generated, which causes a problem that the device characteristics are deteriorated.

The present invention has been made to solve the problems of the prior art, and it is an object of the present invention to provide a semiconductor laser device having a stable transverse mode, a small reactive current, and a low operating voltage. To aim.

[0010]

In a semiconductor laser device according to the present invention, a stripe-shaped groove having at least a (111) plane is formed on the surface side of a p-type GaAs substrate having a (100) plane on the surface. N-doped Zn _y M on the substrate
g _1-y S _z Se _1-z (0 ≦ y ≦ 1, 0 ≦ z ≦ 1) layers are laminated, and further on the N-doped Zn _y Mg _1-y S _z Se _1-z layer.
A p-type clad layer, an active layer and an n-type clad layer made of a II-VI group compound semiconductor are formed, whereby the above object is achieved.

Another semiconductor laser device of the present invention is
A striped groove having a (m11) plane (m is an integer of 3 or more) or a (100) plane as at least one plane is provided on the surface side of the first conductivity type GaAs substrate having a (111) plane on the surface. II-V formed on the substrate in this state
A first conductivity type clad layer, an active layer and a second conductivity type clad layer made of a Group I compound semiconductor are formed, and the first conductivity type clad layer is further formed.
P of the conductivity type clad layer and the second conductivity type clad layer
The type clad layer is N-doped Zn _y Mg _1-y S _z Se _1-z (0 ≦
y ≦ 1, 0 ≦ z ≦ 1), and at least part of the p-type cladding layer is on the (m11) plane (where m is an integer of 3 or more) or (100) plane of the groove. Formed, which achieves the above objectives.

[0012]

As described above, N-doped Zn _y Mg _1-y S _z S
For e _1-z (0 ≦ y ≦ 1, 0 ≦ z ≦ 1), the doping efficiency changes depending on the plane orientation of the GaAs substrate used for epitaxial growth. (311), (511), (71
In the growth on a higher order surface such as 1), the doping efficiency is improved and the p-type carrier concentration is increased as compared with the growth on the (100) surface. On the other hand, when grown on the (111) plane, the doping efficiency is decreased and the resistance is high. These characteristics are observed on both A-plane and B-plane.

In the semiconductor laser device of the present invention, p
Of at least (11
1) A stripe-shaped groove having a surface is formed, and an N-doped Zn _y Mg _1-y S _z Se _1-z layer is laminated on the substrate in this state. The N-doped Zn _y Mg _1-y S _z Se _1-z layer is (11
The portion grown on the (1) plane has a high resistance, and the portion grown on the (100) plane becomes a p-type, so that current confinement can be performed and the reactive current can be reduced.

In another semiconductor laser device of the present invention, at least the (m11) plane (where m is an integer of 3 or more) or (10) on the (111) plane side of the first conductivity type substrate.
N-doped Zn _y Mg _1-y S _z Se _{1-z of the first-} conductivity-type cladding layer and the second-conductivity-type cladding layer formed on the substrate in this state in which stripe-shaped grooves having a (0) plane are formed.
At least a part of the p-type cladding layer composed of (0 ≦ y ≦ 1, 0 ≦ z ≦ 1) is formed on the (m11) plane (m is an integer of 3 or more) or (100) plane of the groove. Has been done.
In the N-doped Zn _y Mg _1-y S _z Se _1-z layer, the portion grown on the (111) plane has a high resistance and the portion grown on the (100) plane becomes p-type, so that the current confinement occurs. Therefore, it is possible to reduce the reactive current. Furthermore, the N-doped Zn _y Mg _1-y S _z Se _1-z grown on the (m11) plane (where m is an integer of 3 or more), which is a high-order plane, has a high p-type carrier concentration. In the case of growing on the (100) plane, as the growth proceeds, the (m11) plane (however,
m is an integer of 2 or more), and particularly when m is 3 or more, the p-type carrier concentration becomes high. The electric resistance of the element can be reduced and the operating voltage can be lowered by using the portion where the p-type carrier concentration is high as the current path. On the other hand, N-doped Zn _y M grown on the (111) plane
Since the g _{1 -y} S _z Se _1-z layer has high resistance, current confinement can be performed, and reactive current can be reduced.

In the semiconductor laser device and other semiconductor laser devices of the present invention, the active layer is bent due to the groove formed on the substrate, and the current flows only just above the groove to become the active region. . Since the energy gap of the GaAs substrate is smaller than the energy gap of the active layer, the light generated in the active region and laterally spread is absorbed by the GaAs substrates on both outer sides of the stripe-shaped groove. Therefore, the lateral spread of light is suppressed, and stable laser oscillation can be achieved in the transverse mode.

[0016]

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

Example 1 FIG. 1 shows a sectional view of a semiconductor laser device of Example 1. This semiconductor laser device is a p-type G
It has an aAs substrate 1, and (11
1) Side surface 2c which is the A surface and bottom surface 2b which is the (100) surface
A stripe-shaped groove 2 having a is formed. Board 1
The upper surface 2a excluding the stripe-shaped groove 2 of is a (100) plane. An N-doped Zn _y Mg _1-y S _z Se _1-z (y = 1, z = 0) buffer layer 4 is laminated over the entire surface of the substrate 1. This N-doped Zn _y Mg _1-y S
_{The z} Se _1-z buffer layer 4 has side surfaces 2 that are (111) A planes.
The portion 3 (hatched portion) grown on c has high resistance,
The portions grown on the upper surface 2a and the bottom surface 2b, which are (100) planes, exhibit p-type conductivity.

On the buffer layer 4, a II-VI group compound
N-doped Zn consisting of conductor_yMg_1-yS_zSe_1-z(Y =
0.9, z = 0.2) Clad layer 5, N-doped Zn_yM
g_1-yS _zSe_1-z(Y = 1, z = 0.06) guide layer
6, Zn_xCd_1-xSe (x = 0.8) active layer 7, Cl
N-type Zn_yMg_1-yS_zSe_1-z(Y = 1, z = 0.0
6) Guide layer 8, Cl-doped n-type Zn_yMg_1-yS_zSe
_1-z(Y = 0.9, z = 0.2) cladding layer 9 and C
The l-doped n-type ZnSe contact layer 10 is applied from the substrate side.
Are laminated in this order. The clad layer 5 and the gas
Both the id layers 6 are formed on the side surface 2c which is the (111) A plane.
The grown part has a high resistance and is a (100) plane.
The portion grown on the surface 2a and the bottom surface 2b has p-type conductivity.
Is shown.

Further, a dielectric film 11 made of SiO ₂ is formed thereon, and an n-type electrode 12 is formed on the dielectric film 11 side.
However, the p-type electrode 13 is formed on the substrate 1 side.

The semiconductor laser device having the above structure is manufactured as follows.

First, as shown in FIG. 1A, p-type Ga is used.
The (100) plane of the upper surface of the As substrate 1 is subjected to ordinary photolithography and etching to form the stripe-shaped grooves 2. At this time, a resist prebaked at a high temperature of 100 ° C. or higher or a normal CVD (Chemical)
A dielectric film (for example, a SiO ₂ film) deposited by the Vapor Deposition method is used as an etching mask, and the stripe direction of the GaAs substrate 1 is formed.

[0022]

[Equation 1]

When wet etching using a mixed solution of sulfuric acid, hydrogen peroxide and water as an etchant was performed in the same direction, (111) A was formed on the upper surface of the GaAs substrate 1.
A stripe-shaped groove having a side surface that is a surface can be formed. In addition, at this time, the side surface 2 that is the (111) A plane is etched by shallow etching with a wide stripe width.
The stripe-shaped groove 2 having c and the bottom surface 2b which is the (100) plane can be produced. In this embodiment, the stripe width is 4.4 μm and the depth of the groove 2 is 1.0 μm.
A stripe-shaped (100) plane having a width of 3 μm was formed on the bottom surface of the groove 2. It should be noted that, as the etchant, a groove having a similar shape can be formed by using a mixed solution of ammonia, hydrogen peroxide solution and water instead of the above.

Next, as shown in FIG. 2 (b), the etching mask is removed, and M is spread over the entire surface of the GaAs substrate 1.
N-doped Zn _y Mg _1-y S _z Se _1-z (y
= 1 and z = 0) The buffer layer 4 is epitaxially grown. At this time, (111) on the side surface 2c of the stripe-shaped groove 2
The portion 3 of the buffer layer 4 grown on the A surface has a high resistance, and the upper surface 2 which is the (100) surface of the GaAs substrate 1 surface.
The buffer layer portion grown on a and the bottom surface 2b becomes p-type.

Then, as shown in FIG. 2 (c), MBE
N-doped Z made of II-VI group compound semiconductor by growth method
n _y Mg _1-y S _z Se _1-z (y = 0.9, z = 0.2) cladding layer 5, N-doped Zn _y Mg _1-y S _z Se _1-z (y = 1,
z = 0.06) guide layer 6, Zn _x Cd _1-x Se (x =
0.8) Active layer 7, Cl-doped n-type Zn _y Mg _1-y S _z S
e _{1 -z} (y = 1, z = 0.06) guide layer 8, Cl-doped n-type Zn _y Mg _1-y S _z Se _{1 -z} (y = 0.9, z = 0.
2) The cladding layer 9 and the Cl-doped n-type ZnSe contact layer 10 are sequentially epitaxially grown. At this time, the N-doped Zn _y Mg _{1- y} S _z Se _1-z cladding layer 5 and the N-doped Zn _y Mg _1-y S _z Se _1-z guide layer 6 are both
The portion grown on the side surface 2c, which is the (111) A plane, has a high resistance, and the portion grown on the upper surface 2a and the bottom surface 2b, which is the (100) plane, is p-type.

Next, a dielectric film 11 made of SiO ₂ is formed by the CVD method, and only the groove 2 is opened in stripes.

Finally, the n-type electrode 12 is provided on the dielectric film 11 side.
The p-type electrode 13 is formed on the substrate 1 side to form a semiconductor laser device.

In this example, the depth and width of the groove 2 and the thickness of each semiconductor layer were formed as follows.

Groove 2: depth 1.0 μm, width 3.0 μ
m N-doped buffer layer 4: thickness 0.08 μm N-doped cladding layer 5: thickness 1.2 μm N-doped guide layer 6: thickness 0.1 μm active layer 7: thickness 0.008 μm n-type guide layer 8: thickness 0.1 μm n Type cladding layer 9: thickness 1.2 μm n-type contact layer 10: thickness 0.2 μm In this semiconductor laser device, the N-doped buffer layer portion 3 grown on the (111) A plane of the side surface 2 c of the stripe groove 2, Each portion of the N-doped clad layer 5 and the N-doped guide layer 6 has high resistance. That is, unlike the prior art, current confinement can be performed with higher efficiency in the high resistance portion of the three layers made of II-VI group compound semiconductor. Further, each portion of the N-doped buffer layer 4, the N-doped clad layer 5 and the N-doped guide layer 6 grown on the (100) plane of the bottom surface 2b of the groove 2 and the upper surface 2a of the GaAs substrate other than the groove 2 is p-type. Is. In addition, the fact that the dielectric film 11 made of SiO ₂ is formed with a stripe-shaped opening also means that the current is (10
0) Flows only in the portion grown on the surface. Therefore, the internal constriction structure of the current is formed, and the reactive current can be reduced. Further, since the internal current constriction structure can be produced by successively epitaxially growing all the layers from the buffer layer 4 to the contact layer 10 once, the production cost can be reduced and the yield can be improved. Further, since the energy gap of the GaAs substrate 1 can be made smaller than that of the active layer 7, the active layer 7
Light generated in the active region located immediately above the groove 2 is absorbed by the GaAs substrate 1 on both outer sides of the stripe groove 2.
Therefore, it is possible to obtain stable laser oscillation in the transverse mode by suppressing the lateral spread of light.

The semiconductor laser device manufactured as described above has an oscillation threshold current of 40 mA and an oscillation wavelength of 500 n.
m, differential efficiency 0.7 W / A, operating voltage 5.0 V,
A stable basic mode was obtained for the transverse mode. Also, the same characteristics were obtained at high light output.

(Embodiment 2) FIG. 3 shows a sectional view of a semiconductor laser device of Embodiment 2. This semiconductor laser device has a p-type GaAs substrate 21, and an upper layer portion of this substrate 21 is
A stripe-shaped groove 22 having a bottom surface 22b which is a (100) plane and a side surface 22c which is a (111) A plane;
1) The stripe-shaped groove 23 having only the side surface 23a which is the A surface is formed. On the upper surface of this substrate 21,
As the (100) plane, the bottom surface 22b of the stripe groove 23 is used.
Only exists. An N-doped Zn _y Mg _1-y S _z Se _1-z (y = 1, z = 0) buffer layer 24 is stacked over the entire surface of the substrate 21. This N-doped Zn _y Mg _1-y
In the S _z Se _1-z buffer layer 24, the portions (hatched portions) grown on the side surfaces 22c and 23a which are (111) A planes have high resistance, and are grown on the bottom surface 22b which is (100) planes. The exposed portion 25 exhibits p-type conductivity. Buffer layer 24
N-doped Zn _y made of II-VI group compound semiconductor
Mg _1-y S _z Se _{1- z} (y = 0.8, z = 0.4) cladding layer 26, N-doped Zn _y Mg _1-y S _z Se _{1- z} (y = 0.
9, z = 0.2) guide layer 27, ZnS _z Se _1-z (z =
0.06) Active layer 28, Cl-doped n-type Zn _y Mg _1-y S
_z Se _1-z (y = 0.9, z = 0.2) guide layer 29, C
1-doped n-type Zn _y Mg _1-y S _z Se _1-z (y = 0.8, z
= 0.4) Cladding layer 30 and Cl-doped n-type ZnS
The e-contact layer 31 is laminated in this order from the substrate side.

Both the N-doped Zn _y Mg _1-y S _z Se _1-z cladding layer 26 and the N-doped Zn _y Mg _1-y S _z Se _1-z guide layer 27 are side surfaces which are (111) A planes. The portions grown on 22c and 23a have high resistance, and (10
The portion grown on the bottom surface 2b, which is the 0) plane, exhibits p-type conductivity. Further, an n-type electrode 32 is provided on the contact layer 31 side.
However, the p-type electrode 33 is formed on the substrate 21 side.

This semiconductor laser device is manufactured as follows.

First, as shown in FIG. 4, the stripe-shaped groove 2 is formed by subjecting the (100) plane of the upper surface of the p-type GaAs substrate 21 to ordinary photolithography and etching.
2, 23 are formed. At this time, the stripe direction of the GaAs substrate 21 is defined by using a resist pre-baked at a high temperature of 100 ° C. or higher or a dielectric film (eg, SiO ₂ film) deposited by a normal CVD method as an etching mask.

[0035]

[Equation 2]

When wet etching using a mixed solution of sulfuric acid, hydrogen peroxide and water as an etchant was performed in the same direction, (111) A was formed on the upper layer of the GaAs substrate 1.
A stripe-shaped groove having a side surface that is a surface can be formed. At this time, the groove 22 having the (100) plane formed on the bottom surface 22b and the groove 23 having no bottom surface can be simultaneously formed by changing the distance between the etching masks. In this embodiment, the width of the etching mask is 0.4 μm, the distance between the etching masks for forming the grooves 22 is 4.0 μm, the distance between the etching masks for forming the grooves 23 is 1.0 μm, and the grooves 22, 23 are formed. The depth was 1.0 μm. As a result, a stripe-shaped (100) surface having a width of 3 μm was formed on the bottom surface 22b of the groove 22, and the bottom surface which was the (100) surface was not formed on the groove 23.
In addition, as the etchant, a groove having a similar shape can be formed by using a mixed solution of ammonia, hydrogen peroxide solution, and water instead of the above-mentioned one.

Then, the etching mask is removed and GaA is removed.
An N-doped Zn _y Mg _1-y S _z Se _1-z (y = 1, z = 0) buffer layer 24 is epitaxially grown on the entire surface of the s substrate 21 by the MBE growth method. At this time, (11 of the side surfaces 22c and 23a of the stripe-shaped grooves 22 and 23 are
1) The buffer layer 24 portion grown on the A surface has a high resistance, and the portion 25 grown on the (100) surface of the bottom surface 22b of the groove 22 becomes p-type.

Then, N-doped Zn _y Mg _1-y S _z Se _1-z (y consisting of a II-VI group compound semiconductor is formed by the MBE growth method.
= 0.8, z = 0.4) Cladding layer 26, N-doped Zn
_y Mg _1-y S _z Se _1-z (y = 0.9, z = 0.2) guide layer 27, ZnS _z Se _1-z (z = 0.06) active layer 28,
Cl-doped n-type Zn _y Mg _1-y S _z Se _1-z (y = 0.9,
z = 0.2) guide layer 29, Cl-doped n-type Zn _y Mg
_{A 1-y} S _z Se _1-z (y = 0.8, z = 0.4) cladding layer 30 and a Cl-doped n-type ZnSe contact layer 31 are sequentially epitaxially grown. At this time, N-doped Zn _y
Mg _1-y S _z Se _1-z cladding layer 26 and N-doped Zn _y
Both the Mg _1-y S _z Se _1-z guide layers 27 are (111) A.
The portions grown on the side surfaces 22c and 23a, which are planes, have a high resistance, and the portions grown on the bottom surface 22b, which is a (100) plane, are p-type.

Finally, an n-type electrode 32 is formed on the contact layer 31 side and a p-type electrode 33 is formed on the substrate 21 side to form a semiconductor laser device.

In this example, the thickness of each semiconductor layer was formed as follows.

N-doped buffer layer 24: thickness 0.08 μm N-doped cladding layer 26: thickness 1.2 μm N-doped guide layer 27: thickness 0.1 μm active layer 28: thickness 0.008 μm n-type guide layer 29: thickness 0. 1 μm n-type cladding layer 30: thickness 1.2 μm n-type contact layer 31: thickness 0.2 μm In this semiconductor laser device, the stripe-shaped groove 22 is used.
The portions of the N-doped buffer layer 24, the N-doped clad layer 26, and the N-doped guide layer 27 grown on the (111) A planes of the side surfaces 22c and 23a of 23 and 23 have high resistance. That is, unlike the prior art, current confinement can be performed with higher efficiency in the high resistance portion of the three layers made of II-VI group compound semiconductor. In addition, the bottom surface 22b of the groove 22
N-doped buffer layer 25 grown on the (100) plane of
Each portion of the N-doped clad layer 26 and the N-doped guide layer 27 is p-type. For this reason, the electric current is applied to the bottom surface 2 of the groove 22.
An internal current confinement structure is formed in which the current flows only in the portion grown on the (100) plane of 2b, so that the reactive current can be reduced. Also in this semiconductor laser device,
Similar to the first embodiment, the manufacturing cost can be reduced and the yield can be improved, and a stable fundamental mode can be obtained in the transverse mode with a low operating current. Further, since the semiconductor laser device of the present embodiment does not require a film corresponding to the dielectric film 11 used in the first embodiment due to the current constriction, the contact area between the electrode 32 and the contact layer 31 is large. Can be taken. Therefore, the contact resistance can be reduced and the operating voltage can be further lowered.

(Embodiment 3) FIG. 5 shows a sectional view of a semiconductor laser device of Embodiment 3. This semiconductor laser device has a p-type GaAs substrate 51, and an upper layer portion of this substrate 51 is
Striped grooves 52 having side faces of (100) plane and (011) plane are formed. The upper surface of the substrate 51 is (111) A except for the stripe-shaped grooves 52.
Is a face. An N-doped Zn _y Mg _1-y S _z Se _1-z (y = 1, z = 0) buffer layer 54 is laminated over the entire surface of the substrate 51. This N-doped Zn _y Mg _1-y
In the S _z Se _{1 -z} buffer layer 54, the portion (shaded portion) grown on the (111) A plane has high resistance, and the portion 53 grown on the (100) plane exhibits p-type conductivity.

On the buffer layer 54, N-doped Zn _y Mg _{1- y} S _z Se _1-z (y =
0.9, z = 0.2) Clad layer 55, N-doped Zn _y
Mg _{1- y} S _z Se _1-z (y = 1, z = 0.06) guide layer 56, Zn _x Cd _1-x Se (x = 0.8) active layer 57, C
l-doped n-type Zn _y Mg _1-y S _z Se _1-z (y = 1, z =
0.06) Guide layer 58, Cl-doped n-type Zn _y Mg _1-y
S _z Se _1-z (y = 0.9, z = 0.2) cladding layer 59
A Cl-doped n-type ZnSe contact layer 60 is formed in this order from the substrate side.

Both the N-doped Zn _y Mg _1-y S _z Se _1-z cladding layer 55 and the N-doped Zn _y Mg _1-y S _z Se _1-z guide layer 56 are formed on the (111) A plane of the substrate 51. The portion grown above (hatched portion) has a high resistance, and (10
The portion grown on the (0) plane exhibits p-type conductivity. Further, the n-type electrode 61 is provided on the contact layer 60 side and the substrate side 5
A p-type electrode 62 is formed on each of the electrodes 1.

This semiconductor laser device is manufactured as follows.

First, ordinary photolithography and etching are performed on the (111) A surface of the upper surface of the p-type GaAs substrate 51 to form the stripe-shaped grooves 52. At this time, a resist prebaked at a high temperature of 100 ° C. or higher or a dielectric film (for example, S
The SiO ₂ film) is used as an etching mask in the stripe direction of the GaAs substrate 51.

[0047]

(Equation 3)

When wet etching is performed using a mixed solution of sulfuric acid, hydrogen peroxide solution and water as an etchant, the (100) plane and the (011) plane are side surfaces on the upper layer portion of the GaAs substrate 1. It is possible to form the stripe-shaped groove 52 included in the above. In this embodiment, the stripe width is 4.0 μm and the depth of the groove 52 is 2.0 μm. In addition,
Instead of the above-mentioned etchant, a groove having a similar shape can be formed by using a mixed solution of ammonia, hydrogen peroxide solution and water.

Then, the etching mask is removed and GaA is removed.
An N-doped Zn _y Mg _1-y S _z Se _1-z (y = 1, z = 0) buffer layer 54 is epitaxially grown on the entire surface of the s substrate 51 by the MBE growth method. At this time, the portion 5 grown on the (100) plane of the side surface of the stripe-shaped groove 52.
3 is a p-type, and (1
11) The portion grown on the A surface has high resistance.

Then, N-doped Zn _y Mg _1-y S _z Se _1-z (y consisting of a II-VI group compound semiconductor is formed by the MBE growth method.
= 0.9, z = 0.2) Cladding layer 55, N-doped Zn
_y Mg _1-y S _z Se _1-z (y = 1, z = 0.06) guide layer 56, Zn _x Cd _1-x Se (x = 0.8) active layer 57, C
l-doped n-type Zn _y Mg _1-y S _z Se _1-z (y = 1, z =
0.06) Guide layer 58, Cl-doped n-type Zn _y Mg _1-y
S _z Se _1-z (y = 0.9, z = 0.2) cladding layer 59
Then, a Cl-doped n-type ZnSe contact layer 60 is sequentially epitaxially grown.

Both the N-doped Zn _y Mg _1-y S _z Se _1-z cladding layer 5 and the N-doped Zn _y Mg _{1- y} S _z Se _1-z guide layer 6 are formed on the (111) A plane of the substrate 51. The portion grown above has a high resistance, and the portion grown on the (100) plane of the substrate 51 becomes p-type. Also, as the growth progresses, the groove 5
The (m11) A plane (however, on the (100) plane of the side surface of 2
When m is an integer of 2 or more) and 3 ≦ m, the carrier becomes a p-type having a high carrier concentration. In addition, N-doped Zn _y Mg _1-y S _z
When the interface between the Se _{1 -z} guide layer 56 and the active layer 57 has a plane orientation of (m11) A plane (where m is an integer of 3 or more), the guide layer 56 has a high resistance at this interface. Can be prevented.

Finally, an n-type electrode 61 is formed on the contact layer 60 side and a p-type electrode 62 is formed on the substrate 51 side to form a semiconductor laser device.

In this embodiment, the depth and width of the groove 52 and the thickness of each semiconductor layer are formed as follows.

Groove 52: Depth 2.0 μm, width 4.0
μm N-doped buffer layer 54: thickness 0.08 μm N-doped cladding layer 55: thickness 1.2 μm N-doped guide layer 56: thickness 0.1 μm active layer 57: thickness 0.008 μm n-type guide layer 58: thickness 0.1 μm n Type clad layer 59: 1.2 μm thickness n-type contact layer 60: 0.2 μm thickness In this semiconductor laser device, (11
1) Each portion (hatched portion) of the N-doped buffer layer 54, the N-doped clad layer 55, and the N-doped guide layer 56 grown on the A surface has high resistance. That is, unlike the prior art, current confinement can be performed with higher efficiency in the high resistance portion of the three layers made of II-VI group compound semiconductor. Further, each portion of the N-doped buffer layer 53, the N-doped clad layer 55 and the N-doped guide layer 56 grown on the (100) surface of the side surface of the groove 52 is p-type. Therefore, an internal current confinement structure is formed in which the current flows only in the portion grown on the (100) plane of the side surface of the groove 52, and the reactive current can be reduced. In addition, in the semiconductor laser device of the present embodiment, the N-doped cladding layer 55 and the N-doped guide layer 56 near the active layer can be grown on the (m11) A plane (where m is an integer of 3 or more). . Therefore, the carrier concentration of holes can be increased to reduce the resistance value of the current path, and the operating voltage can be lowered. Also in this semiconductor laser device, a stable fundamental mode was obtained in the transverse mode with a low operating current as in the first and second embodiments, and the operating voltage could be further lowered. Also,
In the semiconductor laser device of the present embodiment, the dielectric 11 as used in the first embodiment for current constriction and the number of stripe-shaped grooves 23 used in the second embodiment are required. Instead, it is possible to easily fabricate the internal current confinement structure simply by forming one stripe-shaped groove.

In Examples 1 to 3 above, ZnMgSS
The mixed crystal ratio of e may be appropriately changed. Further, as the II-VI group compound semiconductor formed on the GaAs substrate, ZnM is used.
gSSe system, ZnCdSSe system, others, ZnMnSS
Various material systems that form a blue to blue-green semiconductor laser device such as e and ZnSSeTe can be used, and the composition ratio of the compound can be appropriately changed. In addition, (11
Although 1) A-plane and (m11) A-plane (where m is an integer of 3 or more) are used, similar characteristics can be obtained by using B-plane.

In Examples 1 to 3 described above, the guide layer has a uniform composition in the film thickness direction, but the present invention is not limited to this, and the composition of the guide layer changes in the film thickness direction.
-SCH (Graded Index-Separ)
ate Configuration Heterostruct
ure) structure.

In the third embodiment, the conductivity type of the substrate is p-type. However, an n-type GaAs substrate is used and an N-doped Zn _y Mg _1-y S _z Se _1-z guide layer is formed on the active layer. , N-doped Zn _y Mg _1-y S _z Se _1-z cladding layer and N-doped Z
Even when the n _y Mg _1-y S _z Se _1-z contact layer is epitaxially grown, the semiconductor laser device of the present invention can be obtained. Further, although the groove having the (100) plane is formed as the stripe groove, the groove having the (m11) plane (where m is an integer of 3 or more) may be formed.

[0058]

As is apparent from the above description, according to the present invention, the II-V grown on the (111) plane of the substrate is utilized by utilizing the difference in N doping efficiency depending on the plane orientation of the substrate.
Since each layer of the group I compound semiconductor has a high resistance, the current can be confined with higher efficiency, and the operating current can be reduced by reducing the reactive current. Further, since the p-type carrier concentration is increased in the growing portion on the (m11) plane (where m is an integer of 3 or more), the operating voltage can be reduced by using this portion as a current path. Further, since the light generated in the active region of the active layer is absorbed by the GaAs substrate having a small energy gap, laser oscillation can be obtained in a stable transverse mode. Furthermore, since the internal current confinement structure can be formed by one-time epitaxial growth using the MBE method, the semiconductor laser device can be manufactured with high yield and at low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a semiconductor laser device of Example 1.

2A to 2C are cross-sectional views showing a manufacturing process of the semiconductor laser device according to the first embodiment.

FIG. 3 is a sectional view showing a semiconductor laser device of Example 2.

FIG. 4 is a cross-sectional view showing the manufacturing process of the semiconductor laser device according to the second embodiment.

5 is a sectional view showing a semiconductor laser device of Example 3. FIG.

FIG. 6 is a cross-sectional view showing a conventional semiconductor laser device having an electrode stripe structure.

[Explanation of symbols]

1, 21 p-type GaAs substrate 2, 22, 23, 52 stripe-shaped groove 3, 25, 53 portion 4, 24, 54 N-doped Zn _y Mg _1-y S _z Se _1-z buffer layer 5, 26, 55 N Doped Zn _y Mg _1-y S _z Se _1-z cladding layer 6, 27, 56 N-doped Zn _y Mg _1-y S _z Se _1-z guide layer 7, 28, 57 Active layer 8, 29, 58 n-type Guide layer 9, 30, 59 n-type cladding layer 10, 31, 60 n-type contact layer 11 dielectric film 12, 32, 61 n-type electrode 13, 33, 62 p-type electrode

Claims (2)

[Claims] 1. A p-type GaA having a (100) plane on its surface.
A stripe-shaped groove having at least a (111) plane is formed on the surface of the s substrate, and N-doped Zn _y Mg _1-y S _z Se _1-z (0 ≦ y ≦ 1, 0 ≦ is formed on the substrate in this state. z ≦ 1) layers are stacked, and a p-type cladding layer made of a II-VI group compound semiconductor is further formed on the N-doped Zn _y Mg _1-y S _z Se _1-z layer,
A semiconductor laser device having an active layer and an n-type cladding layer. 2. A (m11) plane (where m is an integer of 3 or more) or (10) as at least one plane on the surface side of the first conductivity type GaAs substrate having a (111) plane on its surface.
0) plane stripe-shaped grooves are formed, and a first conductivity type clad layer, an active layer and a second conductivity type clad layer made of a II-VI group compound semiconductor are formed on the substrate in this state. The p-type cladding layer of the conductivity-type cladding layer and the second conductivity-type cladding layer is N-doped Zn _y Mg _1-y S
_z Se _1-z (0 ≦ y ≦ 1, 0 ≦ z ≦ 1), and
At least a part of the p-type clad layer has (m11)
A semiconductor laser device formed on a surface (where m is an integer of 3 or more) or on a (100) surface.