JP2945568B2 - Semiconductor laser device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractive index guided semiconductor laser device having an internal current confinement structure and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, semiconductor laser devices have been actively developed for light sources for optical information processing. Semiconductor laser devices for this application are required to have performances such as small astigmatism, narrow radiation spread angle, and single mode oscillation. An index guided semiconductor laser device has been developed. Conventionally, manufacturing a refractive index guided semiconductor laser device having such an internal current confinement structure requires at least two or more crystal growth steps. However, in consideration of yield and manufacturing cost, it is desirable that a semiconductor laser device can be manufactured in one crystal growth step.

[0003] The inventors of the present invention have proposed, for example, Japanese Patent Application No.
No. 103312 proposes a method for manufacturing a refractive index wave type semiconductor laser device having an internal current confinement structure by one crystal growth step. This manufacturing method utilizes the fact that the conductivity type of the Si-doped GaAs semiconductor layer and the Si-doped AlGaAs layer depends on the plane orientation when the semiconductor layer grows. Hereinafter, the manufacturing process of the semiconductor laser device according to this manufacturing method will be described with reference to FIGS.
This will be described with reference to FIG. 13D and FIGS.

[0004] First, as shown in FIG.
A resist 1110 is applied on an aAs (100) substrate 1101.

[0005] Next, as shown in FIG. 12 (b), a stripe 1100 having a width of 3 μm is formed on the substrate 1101 coated with the resist 1110 by photolithography.

In this state, two kinds of etching solutions, for example, two kinds of a mixed solution of sulfuric acid and hydrogen peroxide solution, are used for the substrate 1101 so that the bottom has a plane orientation (100) as shown in FIG. ) And a side surface 1122 whose side surface portion is a (111) A plane and a plane direction (411).
A groove including the side surface 1123 as the A surface is formed.

Next, as shown in FIG. 12D, the resist 1110 is removed, and the substrate is subjected to a hot sulfuric acid treatment.

[0008] Thereafter, as shown in FIG.
Si-doped GaAs in E (Molecular Beam Epitaxy)
An s current confinement layer 1102 is grown.

Subsequently, as shown in FIG.
p-type Al _x Ga _1-x As (for example, x = 0.50) cladding layer 1104, Al _x Ga _1-x As (for example, x = 0.14)
Active layer 1105, n-type Al _x Ga _{1 -x} As (for example, x =
0.50) A cladding layer 1106 and an n-type GaAs contact layer 1107 are sequentially grown. Further, an n-side electrode 1112 and a p-side electrode 1113 are formed to complete the semiconductor laser device.

By the way, in the MBE method, GaAs doped with Si as an n-type dopant is replaced with (n)
11) It is known that, when a semiconductor layer is grown on a plane of A (1 ≦ n ≦ 3), the adhesion of As is suppressed in the growth process, so that the semiconductor layer is inverted to a p-type. On the other hand, if the plane orientation is (m1
1) On the surface where (m ≧ 4) and the surface where (100),
Such an inversion phenomenon is not observed, and the grown layer becomes n-type.
Such a phenomenon is not observed when another dopant is used.

The following can be considered as a reason for this. That is, the surface having the plane orientation of (n11) A (1 ≦ n ≦ 3) is covered with Ga having one bond, and the adsorbed As has a small adhesion coefficient. Therefore, the impurity Si is easily bonded to Ga and enters the As position. Also,
Increasing the substrate temperature or lowering the As pressure further increases A
The adhesion coefficient of s is reduced, and it becomes easier to show p-type. Therefore, in FIG. 13E, the growth portion 1125 (shaded portion) on the side surface 1122 having the plane orientation of (111) A shows p-type conductivity.

On the other hand, a plane whose plane orientation is (411) A is
Ga having one bond is Ga having two bonds
Less than. Therefore, in FIG. 13E, the growth portion 1126 on the side surface 1123 on both sides of the groove is less likely to be p-type than on the surface 1122 whose plane orientation is (111) A, and becomes n-type. In addition, the surface having a plane orientation of (100) is covered with As having two bonds, and does not become p-type. Therefore, the growth portion 1124 on the bottom surface 1121 at the center of the groove and the growth portion on both outer side portions (flat portions) of the groove are n-type. Therefore, only the growth portion 1125 (shaded portion) on the surface 1122 having the plane orientation of (111) A becomes a current path.

As described above, the current paths are formed on the side surfaces 1 on both sides of the groove.
Since the growth portion 1125 (shaded portion) on the gate 122 is narrowed, the leakage current flowing in the p-type cladding layer 1104 in the lateral direction is reduced, and the threshold current can be reduced.

In this semiconductor laser device,
The flat part 1115 in the active layer 1105 on the groove becomes a light emitting part. This portion is surrounded by the AlGaAs cladding layers 1104 and 1106 having a large energy gap and a small refractive index, and has a real refractive index waveguide structure, so that fundamental transverse mode oscillation can be obtained.

By processing the grooves on the substrate as described above, a refractive index guided semiconductor laser device having an internal current confinement structure can be realized by one crystal growth using the MBE method.

[0016]

In the above-mentioned conventional semiconductor laser device, the (100) plane is used as the bottom surface, and at least (n11) A (1 ≦ n ≦ 3) and (m11) A (m ≧ 4) are used as the side surfaces. ), It is necessary to form a groove having two plane orientations. To form such a groove,
(N11) Two types of etching liquids, an etching liquid that easily obtains the A (1 ≦ n ≦ 3) plane and an etching liquid that easily obtains the (m11) A (m ≧ 4) plane, are used twice. A method of performing etching can be considered. But in this case,
Since the plane orientation obtained by the first etching changes during the second etching, it is difficult to form a groove having a shape as shown in FIG. Accordingly, there is a problem that the yield is reduced and the cost is increased.

The present invention has been made in order to solve the above problems, and an efficient internal current confinement structure capable of reducing a leakage current can be obtained by a single crystal growth process using the MBE method with a high yield. It is an object of the present invention to provide a semiconductor laser device which can be obtained at low cost and a method for manufacturing the same.

[0018]

According to a semiconductor laser device of the present invention, at least the upper and lower surfaces of an active layer comprising a first semiconductor layer are formed by forming a second semiconductor layer having a larger bandgap than the first semiconductor layer. And a third semiconductor layer having a larger bandgap than the first semiconductor layer, the semiconductor laser device including a light emitting laminated portion, wherein the p-type GaAs substrate has a (100) plane as a surface. A V-shaped groove is formed on the surface of the groove in a smooth shape without corners from the groove bottom to the surface, and a Si-doped current confinement comprising one or more layers is formed on the substrate on which the groove is formed. A layer having at least one of the current constriction layers, a bottom surface and both side surfaces having two or more different plane orientations, and p on a plane having at least one plane orientation of the side surfaces. The conductivity of the mold.
The n-type conductivity is formed on a plane other than the plane having one or more plane orientations, and the light emitting laminate is formed on the current confinement layer, thereby achieving the above object. You.

Further, in the semiconductor laser device of the present invention, at least the upper and lower surfaces of the active layer comprising the first semiconductor layer are formed by forming the second semiconductor layer having a larger forbidden band width than the first semiconductor layer and the second semiconductor layer. In a semiconductor laser device having a light emitting laminated portion sandwiched between a third semiconductor layer having a larger forbidden band width than the first semiconductor layer, a p-type Ga having a (100) plane as a surface is provided.
On the surface of the As substrate, a V-shaped groove is formed in a smooth shape with no corners from the groove bottom to the surface, and one or more layers of Si doping are formed on the substrate on which the groove is formed. The current confinement layer has at least one of the current confinement layers.
The layer has a bottom surface portion and two side surface portions having two or more different plane orientations. The layer has p-type conductivity on at least one plane orientation surface of the side surface portions. The n-type conductivity is formed on a surface other than the plane having the above-described plane orientation, and the light emitting laminated portion is formed on the current constriction layer.
Including a Si-doped cladding layer, a part or all of the cladding layer has a bottom surface and both side surfaces having two or more different plane orientations, and has at least one plane orientation of at least one of the side surfaces. The surface shows p-type conductivity and
On the surface other than the surface having one or more plane orientations, it is formed so as to exhibit n-type conductivity, thereby achieving the above object.

[0020] The Si-doped current confinement layer may comprise at least a GaAs layer. The Si-doped current confinement layer is formed of AlGaAs having the same or smaller forbidden band width as at least the second semiconductor layer and the third semiconductor layer.
It may consist of layers. The Si-doped current confinement layer has a larger band gap than at least the GaAs layer and the first semiconductor layer, and has the same or smaller band gap as the second semiconductor layer and the third semiconductor layer. AlG
It may be composed of an aAs layer.

The Si-doped current confinement layer is made of AlGaAs having a bandgap smaller than at least the first semiconductor layer.
An s layer and an AlGaAs layer having the same or smaller forbidden band width as those of the second semiconductor layer and the third semiconductor layer may be used.

The Si-doped current confinement layer has a forbidden band width larger than at least the GaAs layer and the first semiconductor layer, and has a forbidden band width between the second semiconductor layer and the third semiconductor layer. An AlGaAs layer having the same or smaller size and an AlGaAs layer having a larger bandgap than the second semiconductor layer and the third semiconductor layer may be used.

The Si-doped current confinement layer is made of AlGaAs having a bandgap smaller than at least the first semiconductor layer.
an s layer and a forbidden band width larger than that of the first semiconductor layer;
An AlGaAs layer having the same or smaller forbidden band width as the second semiconductor layer and the third semiconductor layer;
And an AlGaAs layer having a larger forbidden band width than the third semiconductor layer.

Further, in the method of manufacturing a semiconductor laser device according to the present invention, at least the upper and lower surfaces of the active layer comprising the first semiconductor layer are formed by forming the second semiconductor layer having a larger forbidden band width than the first semiconductor layer.
In the method for manufacturing a semiconductor laser device having a light emitting laminated portion sandwiched between a semiconductor layer of (1) and a third semiconductor layer having a larger forbidden band width than the first semiconductor layer, Forming a V-shaped groove on the surface of the p-type GaAs substrate in a smooth shape with no corners from the groove bottom to the surface; and forming one layer or a layer on the substrate on which the groove is formed. A Si-doped current confinement layer comprising a plurality of layers, wherein at least one of the current confinement layers has a bottom surface and two or more side surfaces having two or more different plane orientations, and at least one or more of the side surfaces Forming p-type conductivity on a plane having a plane orientation of n, and exhibiting n-type conductivity on a plane other than the one or more planes. Forming the light emitting laminated portion, whereby the There is achieved.

The method of manufacturing a semiconductor laser device according to the present invention comprises:
At least upper and lower surfaces of the active layer made of the first semiconductor layer,
A light emitting laminated portion sandwiched between a second semiconductor layer having a larger forbidden band width than the first semiconductor layer and a third semiconductor layer having a larger forbidden band width than the first semiconductor layer; Forming a V-shaped groove on the surface of a p-type GaAs substrate having a (100) plane as a surface with no corners from the groove bottom to the surface in the method for manufacturing a semiconductor laser device. And forming one or more Si-doped current confinement layers on the substrate on which the grooves are formed, and at least one of the current confinement layers has two or more different plane orientations from the bottom surface. And having p-type conductivity on at least one or more planes of the side surfaces, and n-type conductivity on surfaces other than the one or more planes. And forming on the current confinement layer,
The light-emitting lamination portion includes a Si-doped cladding layer, and a part or all of the cladding layer has a bottom surface and both side surfaces having two or more different plane orientations. Forming p-type conductivity on at least one or more plane orientation planes and showing n-type conductivity on a plane other than the one or more plane orientation planes. Thereby, the above object is achieved.

[0026]

According to the semiconductor laser device of the present invention, (10
A smooth V-shaped groove is formed on the surface of the p-type GaAs substrate whose surface is the 0) plane. An Si-doped current confinement layer is formed on the substrate, at least one of which has a bottom surface and two or more side surfaces having two or more different plane orientations. The current confinement layer exhibits p-type conductivity on at least one of the side surfaces in a plane orientation.
The n-type conductivity is exhibited on surfaces other than the one or more planes. Therefore, this semiconductor laser device has a current injection width of
The growth can be limited to a growth part (p-type part) on at least one or more planes in the side surface part, and the spread of current in the horizontal direction can be reduced.

On the other hand, the flat portion of the active layer, which is the light emitting portion, is surrounded by an AlGaAs cladding layer having a large energy gap and a small refractive index, and has a refractive index waveguide structure. In addition, a semiconductor laser device having excellent characteristics can be obtained.

In the semiconductor laser device of the present invention, the n-type clad layer in the light emitting laminated portion is a Si-doped layer, and all or a part of the n-type clad layer is a bottom surface portion and two or more layers. And both side portions having different plane orientations. It shows p-type conductivity on at least one or more planes of the side surfaces, and n on other than the one or more planes.
Indicates mold conductivity. Therefore, the spread of the current in the n-type cladding layer can be reduced, and the threshold value can be further reduced.

The method for manufacturing a semiconductor laser device according to the present invention comprises:
An internal current confinement structure is formed by forming a V-shaped groove and growing a Si-doped current confinement layer thereon. Therefore, it is not necessary to form a groove having a bottom surface and two or more side surfaces having different plane orientations by etching as in the related art, and a semiconductor laser device can be easily manufactured. Also, as in the case of the Si-doped current confinement layer, the semiconductor laser device having a low threshold current can be easily manufactured by using the n-type clad layer as the Si-doped layer.

[0030]

Embodiments of the present invention will be described below.

(Embodiment 1) FIGS. 1A to 1D and FIGS. 2E to 2G show a manufacturing process of the semiconductor laser device of the embodiment 1, and FIG. 1 shows a cross-sectional view of a semiconductor laser device of Example 1. FIG.

In FIG. 2G, the semiconductor laser device has a (100) plane, which is the surface of the p-type GaAs substrate 1.
A V-shaped groove is formed, and a Si-doped current confinement layer 2 is formed thereon. This current confinement layer 2 has a bottom surface 1
10 and two side surfaces 111 and 112 having different plane orientations in the groove depth direction. The bottom surface 110 is, for example, a (100) plane, and the side surfaces 111 and 112 are
For example, the side surface 111 has a plane orientation of (111) A and the side surface 112 has a plane orientation of (411) A. Side surface portion 122 grown on a plane having plane orientation (111) A
Indicates p-type conductivity, and the other growth portions 121 and 123 indicate n-type conductivity.

On the current confinement layer 2, a Si-doped current confinement layer 3 is formed. On the side surface 111 having the plane orientation (111) A, p-type conductivity is exhibited and the plane orientation (41) is formed.
1) On the side surface 112 of A and on the bottom surface 110 of (100), n-type conductivity is exhibited. Therefore, the current path is limited to the hatched portion indicating p-type conductivity.

The p-type Al _x Ga _{1 -x} As (for example, x = 0.50) cladding layer 4 and the Al _x Ga _{1 -x} As (for example, x = 0) are formed on the current confinement layer 3. .14) Active layer 5 and n-type Al _x Ga _{1 -x} As (for example, x = 0.5)
0) The cladding layers 6 are sequentially stacked, and an n-type GaAs contact layer 7 is stacked on the n-type cladding layer 6. Further, a p-side electrode 12 is formed on the p-type substrate 1 side, and an n-side electrode 13 is formed on the n-type contact layer 7 side.

The cladding layers 4 and 6 are formed of a material having a larger forbidden band width than the active layer 5, and the cladding layer 4, the active layer 5 and the cladding layer 6 constitute a light emitting laminated portion. .

This semiconductor laser device can be manufactured as follows.

First, as shown in FIG.
A resist 10 is formed on the (100) surface of the As substrate 1.

Next, as shown in FIG. 1B, a stripe 100 having a width of 3 μm is formed on the substrate 1 coated with the resist 10 by using a photolithography technique.

The substrate 1 in this state is etched using, for example, a mixed solution of sulfuric acid and hydrogen peroxide solution, and FIG.
As shown in (c), the plane orientation of both sides is (111) A
A V-shaped groove is formed.

Next, as shown in FIG. 1D, after the resist 10 is removed, etching is performed using, for example, a mixed solution of sulfuric acid and hydrogen peroxide, and as shown in FIG.
A V-shaped groove 102 having a smooth corner from the flat surface portion 2 to the inside of the groove is formed.

Then, on the substrate 1 on which the smooth V-shaped groove 102 having no corner is formed, the MBE apparatus is used as shown in FIG.
A Si-doped GaAs current confinement layer 2 as shown in FIG.

Next, as shown in FIG. 2 (g), Si-doped Al _X Ga _{1 -X} As (for example, X =
0.50) The current confinement layer 3 is grown. Then, p-type A
l _x Ga _{1 -x} As (for example, x = 0.50) cladding layer 4, Al _x Ga _{1 -x} As (for example, x = 0.14) active layer 5, n-type Al _x Ga _{1 -x} As ( For example, x = 0.50) A cladding layer 6 and an n-type GaAs contact layer 7 are sequentially grown. Further, the p-side electrode 12 and the n-side electrode 13 are formed to complete the semiconductor laser device.

By the way, the present inventors have conducted an experiment and found that the G-shaped groove 102 was formed on the V-shaped groove 102 by the MBE method.
When an aAs layer or AlGaAs is grown, FIG.
(F) As shown in FIG.
I knew that a shape with two sides could be obtained. For example, the bottom part 110 is on the (100) plane,
11 and 112 are (111) A plane and (411) A
Grow on the surface. At this time, of the side surfaces shown in FIG. 2 (f), the growth layer 122 (shaded portion) grown on the side surface which is the (111) A plane shows p-type conductivity, and The layers 121 and 123 show n-type conductivity. Therefore,
When a semiconductor laser device is manufactured, the plane orientation (111) A
Only the growth layer 122 (shaded area) on the side surface is a current path.

The following are conceivable reasons for this. That is, the surface having the plane orientation of (n11) A (1 ≦ n ≦ 3) is covered with Ga having one bond, and the adhesion coefficient of the adsorbed As is small.
This is because i is easily bonded to Ga and easily enters the As lattice position.

The ease of release of As adsorbed on Ga having one bond depends on the growth conditions. Under growth conditions in which the substrate temperature is relatively low and the amount of As flux is large, As is unlikely to be liberated, and even if the surface is the (111) A surface covered with Ga having one bond, n-type conductivity is obtained. May be indicated. Therefore, it is necessary to select appropriate growth conditions.

As described above, the Si-doped GaAs current confinement layer 2 has a (100) plane at the bottom and a (111) A at the side.
Since it grows into a shape having a plane and a (411) A plane, Si-doped Al _x Ga _{1 -x} As grown on it
(For example, x = 0.50) The current confinement layer 3 is as shown in FIG.
As shown in the figure, only the growth layer (shaded portion) on the side surface 111 which is the (111) A plane shows p-type conductivity, and the growth layers on the other surfaces 110 and 112 have n-type conductivity. Show.

In the Si-doped current confinement layer 2, 2
In the side portions having two or more different plane orientations, the Si-doped current confinement layer 3 grown thereon exhibits p-type conductivity on at least one of the side surface portions having a plane orientation, Any combination may be used as long as it shows n-type conductivity on the other surface. For example, a combination of the (211) A plane and the (311) A plane, a combination of the (755) A plane and the (511) A plane, or 3
A combination of planes having two or more plane orientations may be used.

In the above manufacturing, the dopant of the n-type cladding layer 6 and the n-type contact layer 7 is n
Type dopants can be used. When Si is used, the substrate can be grown to exhibit n-type conductivity by increasing the flux of As by setting the substrate temperature to a relatively low temperature.

In the above-described semiconductor laser device, the flat portion 115 of the active layer 5 becomes a light emitting portion. This portion is surrounded by the AlGaAs cladding layers 4 and 6 having a large energy gap and a small refractive index, and has a real refractive index waveguide structure. Further, since the current path is narrowed to the width of the hatched portion shown in FIG. 2G, the threshold current can be greatly reduced as compared with the conventional semiconductor laser device.

When this semiconductor laser device was manufactured as a DH (double hetero) structure in the 780 nm band, the threshold current was 5 mA.

In the above embodiment, the same effect can be obtained even if the mixed crystal ratio of AlGaAs is appropriately changed.

The mixing ratio of the etching solution used for forming the groove may be appropriately changed, and another etching solution such as a mixed solution of ammonia and hydrogen peroxide may be used, or a combination thereof may be used. .

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

In FIG. 3, in the semiconductor laser device of Example 2, the n-type Al _x Ga _{1 -x} As clad layer 26 is formed of a Si-doped layer similarly to the Si-doped current confinement layers 22 and 23. . Similar to the Si-doped current confinement layer, the n-type cladding layer 26 has a substrate temperature relatively high by MBE and a small amount of As flux to partially or entirely (shaded portion) a p-type. Inverted to conductivity.

As a result, the current path is further narrowed in the n-type Ga _x Al ₁ -x As clad layer 26,
The spread current in the horizontal direction can be further reduced,
The threshold current can be greatly reduced as compared with the semiconductor laser device of the first embodiment.

In this embodiment, other structures can be the same as those in the first embodiment.

(Embodiment 3) FIG. 4 is a sectional view showing a semiconductor laser device of Embodiment 3.

In FIG. 4, the semiconductor laser device of the third embodiment has a Si-doped Ga _x Al _{1 -x} As (for example, x = 0.10) having a smaller forbidden band width than the active layer 35 as a Si-doped current confinement layer. The forbidden band width of the current confinement layer 38 and the active layer 35 is larger than that of the active layer 35, and the forbidden band width of the p-type cladding layer 34 and the n-type cladding layer 36 is the same or smaller.
A doped Al _x Ga _{1 -x} As (for example, x = 0.50) current confinement layer 33 is formed. The current confinement layer is composed of a Si-doped Ga _x Al _1-x As (for example, x = 0.10) current confinement layer 38 and a Si-doped Al _x Ga _1-x As (for example, x = 0.10).
0.50) Since the current confinement layer 33 is formed, the active layer 35
Can further reduce the absorption of the light emitted.

As a result, the p-type cladding layer 34 can be formed thin, so that the leakage current in the horizontal direction can be reduced, and the threshold current can be further reduced.

In this embodiment, other structures can be the same as those of the first or second embodiment.

(Embodiment 4) FIG. 5 is a sectional view showing a semiconductor laser device of Embodiment 4.

In FIG. 5, in the semiconductor laser device of the fourth embodiment, the shape of the groove is further smoothed by etching to form a wider groove. Also in this case, the Si-doped GaAs current confinement layer 42 has a shape having a bottom surface and side surfaces having two or more different plane orientations, for example, a (100) surface at the bottom surface, a (111) A surface at the side surface, and (41
1) Growing on A-plane. In addition, (111)
The growth layer (shaded portion) on the side surface that is the A-plane shows p-type conductivity, and the other growth layers show n-type conductivity. Therefore, also in this semiconductor laser device, the plane orientation (111)
Only the growth layer (shaded area) on the side surface that is the A-plane becomes a current path.

Further, S as a Si-doped current confinement layer
i-doped GaAs current confinement layer 42 and Si-doped Al _x
Ga _1-x As (for example, x = 0.50) p-type Al _x Ga _1-x As (for example, x = 0.5)
0) Si-doped Al _x Ga _{1 -x} As (for example, x = 0.60) having a larger band gap than the cladding layer 44 and the n-type Al _x Ga _{1 -x} As (for example, x = 0.50) cladding layer 46.
An optical confinement layer 49 is formed.

Also in this Si-doped light confinement layer 49, the growth layer (shaded portion) on the side surface which is the (111) A plane in the groove shows p-type conductivity, and the growth layer on the side surface which is the (411) A surface. (1) on the bottom surface which is the (100) plane and on both outer sides of the groove.
The growth layer on the (00) plane shows n-type conductivity. Since the light confinement layer 49 has a smaller refractive index and a larger energy gap than the cladding layer, a very excellent real refractive index waveguide structure without light absorption by the substrate and the current confinement layer can be obtained. Therefore, the leakage current in the horizontal direction is reduced, the threshold current can be further reduced, and higher efficiency can be realized.

In this embodiment, other structures can be the same as those of the first or second embodiment.

(Embodiment 5) FIG. 6 is a sectional view showing a semiconductor laser device of Embodiment 5.

In FIG. 6, the semiconductor laser device according to the fifth embodiment has a Si-doped Al _x Ga _{1 -x} As (for example, x = 0.10) having a smaller bandgap than the active layer 55 as a Si-doped current confinement layer. The current confinement layer 58 and the Si-doped Al _x G
a _1-x As (for example, x = 0.50) p-type doped Al _x Ga _1-x As (for example, x = 0.5)
0) Si-doped Al _x Ga _{1 -x} As (for example, x = 0.60) having a larger bandgap than the cladding layer 54 and the n-type Al _x Ga _{1 -x} As (for example, x = 0.50) cladding layer 56
An optical confinement layer 59 is formed.

Also in this Si-doped light confinement layer 59, the growth layer (shaded portion) on the side surface which is the (111) A plane in the groove shows p-type conductivity, and the growth layer on the side surface which is the (411) A surface. (1) on the bottom surface which is the (100) plane and on both outer sides of the groove.
The growth layer on the (00) plane shows n-type conductivity. Since the light confinement layer 59 has a smaller refractive index and a larger energy gap than the cladding layer, a very excellent real refractive index waveguide structure without light absorption by the substrate and the current confinement layer can be obtained. Therefore, the leakage current in the horizontal direction is reduced, the threshold current can be further reduced, and higher efficiency can be realized. Further, since the current confinement layer is made of Al _x Ga _1-x As, a stronger real refractive index waveguide structure with less light absorption by the substrate and the current confinement layer as compared with the semiconductor laser device of the fourth embodiment. it can.

In this embodiment, other structures can be the same as those of the first or second embodiment.

(Embodiment 6) FIG. 7 is a sectional view showing a semiconductor laser device of Embodiment 6.

In FIG. 7, in the semiconductor laser device of the sixth embodiment, Ga _x Al _{1 -x} As (for example, x = 0.1
0) has a quantum well structure.
Light guide layers 69 and 69 made of Ga _x Al _{1 -x} As (for example, x = 0.35) are provided between the active layer 65 and the cladding layers 64 and 66, respectively.
rate Confinement Heterostructure) or GRIN
(Grade Refractive Index)-It has a SCH structure. According to this structure, light can be sufficiently confined in the active layer 65. Further, since the active layer 65 has a quantum well structure, the threshold current can be further reduced. Other structures can be the same as those of the first to fifth embodiments.

Also, in this embodiment, the Si-doped GaAs layer 62 and the Si-doped Ga
_Although xAl ₁ -xAs (for example, x = 0.50) 63 was formed, even if a current confinement layer similar to that of Examples 2 to 5 was formed, a very strong light without light absorption by the substrate and the current confinement layer was obtained. A real refractive index waveguide structure was obtained, and a sufficient effect was obtained.

(Embodiment 7) FIG. 8 is a sectional view showing a semiconductor laser device of Embodiment 7.

In FIG. 8, the semiconductor laser device of the seventh embodiment is one in which the present invention is applied to a 630 nm band InGaAlP-based red semiconductor laser device. This semiconductor laser device is provided on a (100) plane of a p-type GaAs substrate 71.
A groove similar to that of Example 1 is formed, and Si-doped G
The aAs current confinement layer 72 is formed in a shape having a bottom surface and side surfaces having two or more different plane orientations.
On top of that, p-type (Al _x Ga _1-x ) _y In _1-y P (for example,
x = 0.70, y = 0.51) cladding layer 74 and n
Type (Al _x Ga _1-x ) _y In _1-y P (for example, x = 0.7
0, y = 0.51) Si-doped Al _x Ga _{1 -x} As (for example, x
= 0.50) The current constriction layer 73 is formed, exhibits p-type conductivity on the side surface having the plane orientation (111) A, and has the surface orientation (411) A on the side surface and the plane direction (100).
Shows n-type conductivity on the bottom surface. Therefore, the current path is limited to the hatched portion indicating p-type conductivity.

On the current confinement layer 73, a p-type (Al
_{x Ga 1-x) y In} 1-y P ( e.g., x = 0.70, y =
0.51) Cladding layer 74, (Al _x Ga _1-x ) _y In _1-y
P (for example, x = 0, y = 0.51) active layer 75, n-type (Al _x Ga _1-x ) _y In _1-y P (for example, x = 0.70,
y = 0.51) The cladding layer 76 and the n-type GaAs contact layer 77 are sequentially laminated.

The cladding layers 74 and 76 are made of a material having a larger band gap than the active layer 75. The flat portion of the active layer 75 on the groove serving as the light emitting portion is surrounded by cladding layers 74 and 76 having a large energy gap and a small refractive index, and has a real refractive index waveguide structure. Further, since the current path is narrowed to the width of the hatched portion, the threshold current can be greatly reduced as compared with the conventional semiconductor laser device.

This structure was changed to 630 nm band InGaAlP.
A sufficient effect was obtained even when the present invention was applied to a system-based semiconductor laser device. The semiconductor laser device of this embodiment has an oscillation wavelength of 63
At 3 nm, the threshold current becomes 12 mA, which is the same as the conventional 630 nm.
As a result, lower threshold and higher efficiency can be realized as compared with the InGaAlP-based red semiconductor laser device in the band.

In this embodiment, even if a current confinement layer similar to that of Embodiments 3 to 5 is formed, a very strong real refractive index waveguide structure without light absorption by the substrate and the current confinement layer can be obtained. Sufficient effects were obtained.

(Eighth Embodiment) FIG. 9 is a sectional view showing a semiconductor laser device of an eighth embodiment.

In FIG. 9, the semiconductor laser device of the eighth embodiment is one in which the present invention is applied to a ZnMgSSe-based blue semiconductor laser device in the 470 nm band. This semiconductor laser device is provided on the (100) plane of a p-type GaAs substrate 81.
A groove similar to that of Example 1 is formed, and Si-doped G
The aAs current confinement layer 82 is formed in a shape having a bottom surface and side surfaces having two or more different plane orientations. On top of that, p-type Zn1 _x Mg _1-x SySe _1- y (for example, x =
0.75, y = 0.42) cladding layer 84 and n-type Z
n1 _x Mg _1-x SySe _1- y (for example, x = 0.75, y =
0.42) Si-doped Al _x Ga _{1 -x} As having the same or smaller forbidden band width as the cladding layer 86 (for example, x = 0.5
0) The current confinement layer 83 is formed, and the plane orientation (11
1) p-type conductivity is shown on the side surface A, and n-type conductivity is shown on the side surface 411A and the bottom surface 100. Therefore, the current path is limited to the hatched portion indicating p-type conductivity.

Further, a p-type Z
n1 _x Mg _1-x SySe _1- y (for example, x = 0.75, y =
0.42) Cladding layer 84, Zn1 _x Mg _1-x SySe _1-
y (for example, x = 1, y = 0) active layer 85, n-type Zn1 _x
Mg _1-x SySe _1- y (for example, x = 0.75, y = 0.
42) A cladding layer 86 and an n-type GaAs contact layer 87 are sequentially laminated.

The cladding layers 84 and 86 are formed of a material having a larger forbidden band width than the active layer 85. The flat portion of the active layer 85 on the groove serving as the light emitting portion has a clad layer 84 having a large energy gap and a small refractive index.
86, and has a real refractive index waveguide structure.
Further, since the current path is narrowed to the width of the hatched portion, the threshold current can be greatly reduced as compared with the conventional semiconductor laser device.

The structure was changed to ZnMgSSe in the 470 nm band.
A sufficient effect was obtained even when the present invention was applied to a system-based semiconductor laser device. The semiconductor laser device of this embodiment has an oscillation wavelength of 47.
At 8 nm, the threshold current becomes 20 mA, which is the same as the conventional 470 nm.
As a result, a lower threshold and higher efficiency can be realized as compared with the ZnMgSSe-based blue semiconductor laser device in the band.

In this embodiment, even if a current confinement layer similar to that of Embodiments 3 to 5 is formed, a very strong real refractive index waveguide structure without light absorption by the substrate and the current confinement layer can be obtained. Sufficient effects were obtained.

(Embodiment 9) FIG. 10 is a sectional view showing a semiconductor laser device of Embodiment 9.

In FIG. 10, in the semiconductor laser device of the ninth embodiment, a groove similar to that of the first or fourth embodiment is formed on the (100) plane of the p-type GaAs substrate 91, and the S groove is formed thereon.
The i-doped GaAs current confinement layer 92 is formed in a shape having a bottom surface and side surfaces having two or more different plane orientations. Of the side surfaces, the growth layer (shaded portion) on the (111) A side surface shows p-type conductivity, and the other growth layers show n-type conductivity. Therefore, the plane orientation (111) A
Only the growth layer (shaded area) on the side surface is a current path, and an internal current confinement structure is obtained. The flat portion of the active layer 95 on the groove serving as the light emitting portion is surrounded by cladding layers 94 and 96 having a large energy gap and a small refractive index, and has a real refractive index waveguide structure.

As described above, even when the Si-doped current confinement layer is a single layer, a real refractive index guided semiconductor laser device having an internal current confinement structure can be realized.

(Embodiment 10) FIG. 11 is a sectional view showing a semiconductor laser device of Embodiment 10.

In FIG. 11, in the semiconductor laser device of Example 10, a groove similar to that of Example 1 or Example 4 was formed on the (100) plane of a p-type GaAs substrate 1001, and a p-type cladding layer was formed thereon. 1004 and n-type cladding layer 1
Si-doped Al with the same or smaller forbidden band width as 006
_x Ga _1-x As (for example, x = 0.50) current confinement layer 10
03 is formed. This Si-doped current confinement layer 10
03 has a bottom surface portion and a side surface portion having two or more different plane orientations. Of the side surface portions, (11)
1) The growth layer (shaded portion) on the side surface that is the A-plane shows p-type conductivity, and the other growth layers show n-type conductivity. Therefore, only the growth layer (shaded portion) on the side surface having the plane orientation (111) A serves as a current path, and an internal current confinement structure is obtained. Further, the flat portion of the active layer 1005 on the groove serving as the light emitting portion is surrounded by cladding layers 1004 and 1006 having a large energy gap and a small refractive index, and has a real refractive index waveguide structure.

As described above, even when the Si-doped current confinement layer is a single layer, a real refractive index guided semiconductor laser device having an internal current confinement structure can be realized.

The present invention is not limited to the material system shown in the above embodiment, but may be any material system using a GaAs substrate.
It can be applied to any of them. For example, AlGaI
nN-based, ZnCdSSe-based, Cu (AlGa) (SS
e) Various material systems such as ₂ can be used. Further, the composition ratio of the compound can be appropriately changed.

[0092]

As described above, according to the present invention, the current injection width can be limited to the growth portion (p-type portion) on at least one or more of the side surfaces, and the width in the horizontal direction can be reduced. Leakage current can be greatly reduced. In terms of optical characteristics, since the flat portion of the active layer is surrounded by the AlGaAs cladding layer having a large energy gap and a small refractive index, a real refractive index waveguide structure can be obtained. Therefore,
A lower threshold value and higher efficiency can be realized, and a highly reliable semiconductor laser device can be obtained.

Further, an efficient internal current confinement structure can be formed by one crystal growth step using the MBE method. Therefore, a refractive index guided semiconductor laser device having an internal current confinement structure can be manufactured with high yield and at low cost.

[Brief description of the drawings]

FIGS. 1A to 1D are diagrams illustrating a manufacturing process of a semiconductor laser device of Example 1. FIGS.

FIGS. 2 (e) to 2 (g) are diagrams showing a manufacturing process of the semiconductor laser device of Example 1. FIGS.

FIG. 3 is a cross-sectional view illustrating a semiconductor laser device according to a second embodiment.

FIG. 4 is a sectional view showing a semiconductor laser device according to a third embodiment.

FIG. 5 is a sectional view showing a semiconductor laser device according to a fourth embodiment.

FIG. 6 is a sectional view showing a semiconductor laser device according to a fifth embodiment.

FIG. 7 is a cross-sectional view illustrating a semiconductor laser device according to a sixth embodiment.

FIG. 8 is a sectional view showing a semiconductor laser device of Example 7;

FIG. 9 is a sectional view showing a semiconductor laser device according to an eighth embodiment.

FIG. 10 is a sectional view showing a semiconductor laser device of Example 9;

FIG. 11 is a sectional view showing a semiconductor laser device of Example 10;

FIGS. 12 (a) to 12 (d) are views showing a manufacturing process of a conventional semiconductor laser device.

FIGS. 13 (e) and 13 (f) are views showing a manufacturing process of a conventional semiconductor laser device.

[Explanation of symbols]

1,21,31,41,51,61,71,81,9
1,1001 p-type GaAs substrate 2,22,42,62,72,82,92 Si-doped GaAs current confinement layer 3,23,33,38,43,53,58,63,7
3,83,1003Si-doped AlGaAs current confinement layer 4,24,34,44,54,64,74,84,9
4,1004 p-type cladding layer 5,25,35,45,55,65,75,85,9
5,1005 Active layer 6,26,36,46,56,66,76,86,9
6,1006 n-type cladding layer 7,27,37,47,57,67,77,87,9
7,1007 n-type contact layer 12,212,312,412,512,612,71
2,812,912,1012 p-side electrode 13,213,313,413,513,613,71
3,813,913,1013 n-side electrode 49,59 Si-doped AlGaAs light confinement layer 69 light guide layer

Claims (10)

(57) [Claims] At least the upper and lower surfaces of an active layer formed of a first semiconductor layer are formed on a second semiconductor layer having a larger forbidden band width than the first semiconductor layer, and a forbidden band is wider than the first semiconductor layer. In a semiconductor laser device including a light emitting laminated portion sandwiched between a third semiconductor layer having a large width, a V-shaped groove is formed on the surface of a p-type GaAs substrate having a (100) plane as a surface. One or more Si-doped current confinement layers are formed on the substrate on which the groove is formed in a smooth shape with no corners from the groove bottom to the surface and at least one of the current confinement layers And the bottom and 2
Side surfaces having two or more different plane orientations, and exhibiting p-type conductivity on at least one or more plane orientations of the side faces, and excluding the one or more plane orientations. A semiconductor laser device formed to exhibit n-type conductivity, and the light-emitting lamination portion being formed on the current confinement layer. 2. The method according to claim 1, wherein at least the upper and lower surfaces of the active layer made of the first semiconductor layer have a second semiconductor layer having a larger forbidden band width than the first semiconductor layer, and a forbidden band larger than the first semiconductor layer. In a semiconductor laser device including a light emitting laminated portion sandwiched between a third semiconductor layer having a large width, a V-shaped groove is formed on the surface of a p-type GaAs substrate having a (100) plane as a surface. One or more Si-doped current confinement layers are formed on the substrate having a smooth shape with no corners from the groove bottom to the surface and having at least one of the current confinement layers. Layer the bottom and 2
Side surfaces having two or more different plane orientations, and exhibiting p-type conductivity on at least one or more plane orientations of the side faces, and excluding the one or more plane orientations. Is formed so as to exhibit n-type conductivity. On the current confinement layer, the light emitting laminated portion includes a Si-doped cladding layer, and part or all of the cladding layer is formed on the bottom surface. And p-type conductivity on at least one or more planes of the side parts, and the one or more plane orientations. A semiconductor laser device formed to exhibit n-type conductivity on surfaces other than the surface of the above. 3. The semiconductor laser device according to claim 1, wherein said Si-doped current confinement layer comprises at least a GaAs layer. 4. The semiconductor device according to claim 1, wherein the Si-doped current confinement layer comprises an AlGaAs layer having at least the same or smaller band gap as the second semiconductor layer and the third semiconductor layer.
Or the semiconductor laser device according to 2. 5. The Si-doped current confinement layer has a larger band gap than at least the GaAs layer and the first semiconductor layer, and has a band gap between the second semiconductor layer and the third semiconductor layer. 3. The semiconductor laser device according to claim 1, wherein the semiconductor laser device comprises the same or smaller AlGaAs layer.
6. An AlGa having a forbidden band width smaller than at least the first semiconductor layer in the Si-doped current confinement layer.
3. The semiconductor laser device according to claim 1, comprising an As layer and an AlGaAs layer having the same or smaller forbidden band width as the second semiconductor layer and the third semiconductor layer. 7. The Si-doped current confinement layer has a bandgap wider than at least the GaAs layer and the first semiconductor layer, and has a bandgap with the second semiconductor layer and the third semiconductor layer. 2. An AlGaAs layer having the same or smaller width, and an AlGaAs layer having a larger forbidden band width than the second semiconductor layer and the third semiconductor layer.
Or the semiconductor laser device according to 2. 8. The semiconductor device according to claim 1, wherein said Si-doped current confinement layer has an AlGa having a smaller forbidden band width than at least said first semiconductor layer.
An AsGaAs layer, an AlGaAs layer having a larger bandgap than the first semiconductor layer, and having the same or smaller bandgap as the second semiconductor layer and the third semiconductor layer; 3. The semiconductor laser device according to claim 1, comprising an AlGaAs layer having a forbidden band width larger than that of the first semiconductor layer and the third semiconductor layer. 9. A semiconductor device comprising: a second semiconductor layer having a bandgap wider than the first semiconductor layer; and a forbidden band wider than the first semiconductor layer. In a method for manufacturing a semiconductor laser device having a light emitting laminated portion sandwiched between a third semiconductor layer having a large width, a V-shaped groove is formed on a surface of a p-type GaAs substrate having a (100) plane as a surface. Forming a smooth shape having no corners from the bottom of the groove to the surface; and forming one or more Si-doped current confinement layers on the substrate on which the groove is formed by forming the current confinement layer At least one layer has a bottom surface and both side surfaces having two or more different plane orientations, and exhibits p-type conductivity on a plane having at least one plane orientation among the side surfaces; The n-type conductivity on a surface other than the one or more plane orientations. Forming a Suyo, on of the current confinement layer, a method of manufacturing a semiconductor laser device including the step of forming the light emitting laminate portion. 10. A semiconductor device comprising: a second semiconductor layer having a forbidden band width larger than that of the first semiconductor layer; and a forbidden band of which is larger than the first semiconductor layer. In a method for manufacturing a semiconductor laser device having a light emitting laminated portion sandwiched between a third semiconductor layer having a large width, a V-shaped groove is formed on a surface of a p-type GaAs substrate having a (100) plane as a surface. Forming a smooth shape having no corners from the bottom of the groove to the surface; and forming one or more Si-doped current confinement layers on the substrate on which the groove is formed by forming the current confinement layer At least one layer has a bottom surface and two or more side surfaces having two or more different plane orientations, and exhibits p-type conductivity on a plane having at least one plane orientation among the side surface parts. And n-type conductivity on a plane other than the plane having the one or more plane orientations. And forming the light emitting laminated portion on the current confinement layer, including a Si-doped cladding layer, wherein a part or all of the cladding layer has a bottom surface portion and two or more Side surfaces having different plane orientations, and exhibit p-type conductivity on at least one or more planes of the side faces, and on a plane other than the one or more planes. forming the semiconductor laser device so as to exhibit n-type conductivity.