JPH0613698A - Semiconductor device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide a first layer made of GaAs and a second layer made of GaAlAs having a relatively large Al composition ratio formed on the first layer by liquid crystal growth. By preventing the melt-back at the interface with the layer, the irregularities at the interface can be eliminated, and the Al composition ratio, the doping concentration, etc. can be selected to the optimum values, so that the electron injection efficiency can be improved and high performance can be achieved. An object is to provide a semiconductor device such as a semiconductor laser device. A semiconductor device comprising: a first layer made of GaAs; and a second layer made of GaAlAs having a relatively large Al composition ratio formed on the first layer by liquid crystal growth. , Before forming the second layer on the first layer, on the first layer, the Al composition ratio of the second layer Al
Meltback prevention layers 13 and 24 made of GaAlAs and oxidation prevention layers 14 and 25 made of GaAs, which have composition ratios close to each other.
Is formed by a method other than the liquid crystal growth method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a first layer made of GaAs and an Al composition ratio formed on the first layer by liquid crystal growth that is relatively large.
The present invention relates to a semiconductor device, for example, a semiconductor laser device, including a second layer made of aAlAs.

[0002]

2. Description of the Related Art Conventionally, for example, CS having an oscillation wavelength of 780 nm band CS
The P-type semiconductor laser device is configured as shown in FIG. That is, in FIG. 3, the semiconductor laser device 1
Is a substrate 2 made of GaAs, an n-type cladding layer 3 made of n ⁺ -type GaAl _0.45 As doped with a group VI element such as tellurium, and an active layer 4 made of GaAl _0.15 As.
And a p-clad layer 5 composed of p ⁺ -type GaAl _0.45 As
A p-cap layer 6 made of p ^{+ -type} GaAs and a window 7
It is composed of an insulating layer 7 having a and a metal electrode 8. An electrode layer (not shown) is provided on the lower surface of the substrate 2, and a groove 9 is formed in the substrate 2 from the upper surface of the substrate 2. It is provided in. Mixed crystal ratio of Al (0.45 and 0.1
5) is optimized according to the oscillation wavelength.

In the semiconductor laser device 1 having the above-described structure, the groove 9 is first formed on the surface of the substrate 2 by etching or the like during manufacturing, and the n-clad layer 3, is formed by the LPE (liquid phase crystal growth) method. Active layer 4, p-clad layer 5
And the cap layer 6 are sequentially grown to form an insulating layer 7 thereon, and finally, the lower surface of the substrate 2 and the insulating layer 7 are formed.
It is manufactured by forming an electrode on the upper surface of.

[0004]

However, according to the semiconductor laser device 1 having such a structure, an n ^{+ type} GaAl having a relatively large Al composition ratio in which a group VI element is doped is formed on the substrate 2 made of GaAs. N consisting of _0.45 As
-The clad layer 3 is made to undergo liquid crystal growth,
In this case, due to the occurrence of meltback, the shape of the groove 9 provided on the upper surface of the substrate 2 is destroyed, and a semiconductor laser device having desired performance cannot be obtained.

Further, if the meltback is large, the interface between the substrate 2 and the n-clad layer 3 may be roughened in some cases, resulting in unevenness in a portion which should be flat. Further, there is a problem that the performance of the semiconductor laser device is deteriorated.

In view of the above points, the present invention provides a first layer made of GaAs and a second layer made of GaAlAs having a relatively large Al composition ratio formed on the first layer by liquid crystal growth. By preventing the melt-back at the interface with the layer, the irregularities at the interface can be eliminated, and the Al composition ratio, the doping concentration, etc. can be selected to the optimum values, so that the electron injection efficiency can be improved and high performance can be obtained. It is an object to provide a semiconductor device such as a semiconductor laser device.

[0007]

The above object is to provide a first layer made of GaAs and a second layer made of GaAlAs having a relatively large Al composition ratio formed on the first layer by liquid crystal growth. In a semiconductor device including a first layer, and an Al composition ratio of the second layer on the first layer before forming the second layer on the first layer. GaA close to
The present invention is achieved by a semiconductor device, wherein the meltback prevention layer made of 1As and the oxidation prevention layer made of GaAs are formed by a method other than the liquid crystal growth method.

[0008]

According to the above structure, even when the Al composition ratio of the second layer is relatively large, the meltback prevention layer and the antioxidant layer are provided between the first layer and the second layer. Is formed by a method other than the liquid crystal growth method, so that meltback does not occur during the formation of the meltback preventing layer and the antioxidant layer.

When the n-clad layer is grown on the antioxidant layer by liquid crystal growth due to the presence of the meltback preventing layer and the antioxidant layer, the meltback occurs on the surface of the antioxidant layer. However, even if the antioxidant layer is destroyed by meltback, a meltback inhibitor layer having an Al composition ratio similar to that of the n-clad layer is present below the antioxidant layer. Therefore, since meltback does not occur in the meltback layer, meltback does not occur at all on the surface of the substrate.

Therefore, by keeping the upper surface of the substrate smooth, the shape of the groove is not deformed, and the Al composition ratio, the doping concentration, etc. can be selected to the optimum values, and the electron injection efficiency is improved. It is improved and therefore high performance is obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. FIG. 1 shows C constructed according to the present invention.
An example of an SP type semiconductor laser device is shown.

The semiconductor laser device 10 is an n ^{+ type} GaA.
After forming the groove 12 on the surface of the substrate 11 made of s by etching or the like, a method other than the LPE method, for example, MOC
By the VD method, the MBE method, etc., the melt-back prevention layer 13 made of n ⁺ -type GaAl _x As and the oxidation prevention layer 14 made of n ^{+ -type} GaAs are formed.

Then, by the LPE method, an n-clad layer 15 made of n ^{+ type} GaAl _0.45 As doped with a group VI element such as tellurium, an active layer 16 made of GaAl _0.15 As, and p ^{+ type} GaAl _0.45. A p-clad layer 17 made of As and a p-cap layer 18 made of p ^{+ -type} GaAs are sequentially grown.

Thereafter, a window 19a is formed on the cap layer 18.
And the metal electrode 19b are formed, and the lower surface of the substrate 11 is provided with an electrode layer (not shown).

Here, the melt-back preventing layer 16 has an Al composition ratio x of 0.
It is selected to be smaller than 45 and preferably close to 0.45.

The semiconductor laser device 10 according to the present invention is
With the above configuration, the meltback prevention layer 13 and the oxidation prevention layer 14 are formed between the substrate 11 and the n-clad layer 15 by a method other than the liquid crystal growth method. No meltback occurs during formation of the meltback prevention layer 13 and the antioxidant layer 14.

When the n-clad layer 15 is grown on the antioxidant layer 14 by liquid crystal growth, the meltback preventing layer 13 and the antioxidant layer 14 are present on the substrate 11. , An antioxidant layer 1 having the same composition as the substrate 11
On the surface of No. 4, meltback will occur.

Here, even if the antioxidant layer 14 is destroyed by meltback, the meltback preventive layer below the antioxidant layer 14 has an Al composition ratio similar to that of the n-clad layer. Since the melt back layer 13 exists, melt back does not occur in the melt back layer 13.

Thus, no meltback occurs on the surface of the substrate 11, and therefore the substrate 1
The surface of No. 1 is kept smooth, the groove 12 provided in the substrate 11 does not lose its shape, and the n-cladding layer 15 can be selected to have an optimum Al composition ratio. At the same time, the doping concentration can be selected as an optimum value. Thus, the high-performance semiconductor laser device 10 can be obtained.

FIG. 2 illustrates a VS constructed in accordance with the present invention.
1 shows an essential part of an IS type semiconductor laser device. In this case, the semiconductor laser device 20 is formed on a surface of a substrate 21 made of p ^{+ -type} GaAs by a liquid crystal growth method or the like.
After crystal growth of the current confinement layer 22 made of ^{+ -type} GaAs, stripe-shaped grooves 23 extending from the surface of the current confinement layer 22 to the inside of the substrate 21 are formed by etching or the like.

Subsequently, the meltback layer 24 and the antioxidant layer 25 described above are formed by a method other than the LPE method, and the p-clad layer 26 and the like of p ^{+ -type} GaAlAs are sequentially grown to form a structure. Has been done.

In this case as well, meltback does not occur on the surfaces of the substrate 21, the current confinement layer 22 and the stripe-shaped grooves 23 when the p-cladding layer 26 is grown by liquid crystal growth. The substrate 21 and the current confinement layer 2
The shapes of the groove 2 and the stripe-shaped groove 23 can be held smoothly without breaking, and the same effect as in the case of the embodiment of FIG. 1 can be obtained.

In each of the above embodiments, GaA is formed on the substrate made of GaAs of the semiconductor laser device.
The case where the liquid crystal growth of the clad layer made of lAs has been described, but the present invention is not limited to this, and it is possible to
It is obvious that the present invention can be applied to a semiconductor device having a so-called hetero structure, such as a light emitting diode, which is formed by growing a GaAlAs layer by liquid crystal crystal growth.

[0024]

As described above, according to the present invention, G
a first layer made of aAs and GaA having a relatively large Al composition ratio formed on the first layer by liquid crystal growth.
By preventing meltback at the interface with the second layer of lAs, the above interface irregularities are eliminated and Al
By making it possible to select the composition ratio, the doping concentration and the like to the optimum values, it is possible to improve the electron injection efficiency and to provide a semiconductor device such as a semiconductor laser device having an extremely high performance.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing a main part of an embodiment of a semiconductor laser device according to the present invention.

FIG. 2 is a partial cross-sectional view showing a main part of another embodiment of the semiconductor laser device according to the present invention.

FIG. 3 is a partial cross-sectional view showing an example of a conventional semiconductor laser device.

[Explanation of symbols]

 10 Semiconductor Laser Device 11 Substrate 12 Groove 13 Meltback Prevention Layer 14 Antioxidation Layer 15 n-Clad Layer 16 Active Layer 17 p-Clad Layer 18 Cap Layer 19 Insulating Layer 19a Window 19b Metal Electrode 20 Semiconductor Laser Device 21 Substrate 22 Current Constriction Layer 23 Striped groove 24 Meltback prevention layer 25 Antioxidation layer 26 p-clad layer

Claims (1)

[Claims] 1. A semiconductor including a first layer made of GaAs and a second layer made of GaAlAs having a relatively high Al composition ratio formed on the first layer by liquid phase crystal growth. In a device, before forming a second layer on the first layer, a meltback prevention comprising GaAlAs on the first layer, the Al composition ratio of which is close to the Al composition ratio of the second layer. A semiconductor device, wherein the layer and the antioxidation layer made of GaAs are formed by a method other than the liquid crystal growth method.