JPH06204605A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor laser device oscillated at room temperature by current infection by forming a clad layer and a guide layer, compositions of which are both kept within specific ranges. CONSTITUTION:A distortion superlattice active layer 5 and clad layers 3, 7 consisting of In1-X-YGaXAlYP1-ZAsZ (wherein the values of X, Y and Z are kept within the ranges of 0<=X<=1, 0<=Y<=1, 0.5<=X+Y<=1 and 0<=0.5) are formed onto a substrate 1. Guide layers 4, 6 composed of In1-X-YGaXAlYP1-ZAsZ (wherein the values of X, Y and Z are kept within the ranges of 0<=X<=1, 0<=Y<=1, 0<=X+Y<=1 and 0<=Z<=1) are disposed while being adjoined to the distortion superlattice active layer 5. Accordingly, a semiconductor laser device oscillated by current injection even at room temperature is acquired. The mixed- crystal compositions X, Y and Z of the guide layers 4, 6 not necessarily required to be constant, and may be changed continuously in the film thickness direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device manufactured on a Si or GaP substrate crystal.

[0002]

Are described in the Related Art JP _{63-197391 In 1-xy Ga x Al} y P 1-z As z ( although x, y,
The value of z is 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0.5 ≦ x + y ≦
The semiconductor laser device having a cladding layer of (1, 0 ≦ z ≦ 0.5) as a cladding layer is characterized in that the oscillation wavelength can be selected in a wide range. In addition, since a Si substrate can be used as the substrate crystal, it becomes possible to form a semiconductor laser monolithically with an electronic element, and the OEIC can be formed.
Application to (optical and electronic integrated circuits) is expected.

[0003]

In the above conventional semiconductor laser device, the lattice constant of the active layer is different from the lattice constant of the cladding layer, and the active layer is distorted. When crystal defects occur in the active layer, the characteristics of the laser device are significantly deteriorated. Therefore, the thickness of the active layer must be thin so that crystal defects do not occur. However, if the active layer is too thin, it becomes difficult to efficiently inject carriers into the active layer due to current injection. Therefore, there is a problem that it is difficult to oscillate this laser at room temperature by injecting current.

An object of the present invention is In _1-xy Ga _x Al _y P.
_1-z As _z (where x, y, and z are 0 ≦ x ≦ 1, 0 ≦
It is intended to provide a semiconductor laser device which oscillates at room temperature by current injection, with a cladding layer of y ≦ 1, 0.5 ≦ x + y ≦ 1, 0 ≦ z ≦ 0.5).

[0005]

In order to achieve the above object, a semiconductor laser device of the present invention comprises a strained active layer, an In _1-xy Ga _x Al _y P _1-z As _z (provided that x, y,
The value of z is 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0.5 ≦ x + y ≦
1, 0 ≦ z ≦ 0.5) and adjacent to the strained active layer, In _1-xy Ga _x A
l _y P _1-z As _z (where x, y, and z are 0 ≦ x ≦
1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1, and 0 ≦ z ≦ 1)).

The mixed crystal composition x, y, z of the guide layer
Does not necessarily have to be constant, and may be continuously changed in the film thickness direction.

[0007]

As an example, a laser using AlP as a cladding layer, GaAs as an active layer and Al _y Ga _1-y P as a guide layer will be described with reference to the band diagram near the active layer shown in FIG.

AlP which is the clad layer and G which is the active layer
Since the lattice constant differs from that of aAs by about 4%, the thickness of the active layer must be about 3 nm or less. The thickness of the guide layer adjacent to the active layer is about _{30nm, Al y Ga 1-y} P a guide layer does not occur crystal defects because they have substantially the same lattice constant as AlP cladding layer. Guide layer A
When the mixed layer composition y was changed from 1 to 0 or from 0 to 1 in the film thickness direction so that the band gap of l _y Ga _{1 -y} P changed parabolically as shown in FIG. 1, current was injected even at room temperature. Carriers can be recombined or emitted in the GaAs layer, which is an active layer.

The bandgap of the guide layer is parabolically changed in order to more efficiently inject carriers into the active layer, but the bandgap of the guide layer is not continuous but stepwise. Even if it does, it has the effect of improving the injection efficiency.

[0010]

EXAMPLE 1 FIG. 2 is a structural sectional view of an example of a semiconductor laser device to which the present invention is applied. In FIG. 2, 1 is an n-type Si substrate, 2 is an n-type GaP buffer layer (100 nm), 3 is an n-type AlP clad layer (1 μm).
m) and 4 are n-type Al _y Ga _1-y P guide layers (30 nm),
5 is a non-doped GaAs layer (2 nm) and a non-doped Ga
A strained superlattice active layer in which P layers (1 nm) are alternately laminated three times, 6 is a P-type Al _y Ga _1-y P guide layer (30 nm), 7
Is a p-type AlP clad layer (1 μm), and 8 is a p-type GaP cap layer (100 nm). Each of the above layers was continuously crystal-grown on the n-type Si substrate 1 by a metal organic chemical vapor deposition method. Al _y Ga _1-y P guide layer mixed crystal composition y
1 was changed in the film thickness direction in the range of 1 to 0 and 0 to 1 so that the band gap changed parabolic as shown in FIG.

The grown wafer was provided with a current confinement layer 9 made of a silicon nitride film, a p-type electrode 10 and an n-type electrode 11 and cleaved into 300 μm square chips to form chips. Since the p-type AlP of the clad layer is exposed on the cleavage surface, it was coated with a silicon nitride film in order to prevent deliquescence. When a current was injected into the semiconductor laser device thus manufactured, a red laser beam was oscillated at room temperature.

In this embodiment, the guide layer is Al _y Ga _1-y P, but the guide layer is AlP _1-z As _z and the mixed crystal composition z is 0 to 0. It may be changed in the film thickness direction within the range of 5.

Example 2 In this example, the cladding layer was In _0.01 Ga _0.01 Al _0.98 P _0.98 As _0.02 and the guide layer was In _0.1 Ga _0.9 P _0.8 As _0.2 . About 1 between the two
There is a% lattice mismatch. In addition, In _0.5 Ga _0.5 P having a lattice mismatch of about 4% was used for the active layer to form a single quantum well. As in Example 1, the n-type GaP buffer layer (100 nm) and the n-type In _0.01 Ga _0.01 Al _0.98 P _0.98 were formed on the n-type GaP substrate by using the metal organic chemical vapor deposition method.
As _0.02 clad layer (1 μm), n-type In _0.1 Ga _0.9 P
_0.8 As _0.2 guide layer (30 nm), undoped In _0.5
Ga _0.5 P strained single quantum well active layer (3 nm), P-type In
_0.1 Ga _0.9 P _0.8 As _0.2 Guide layer (30 nm), p-type I
n _0.01 Ga _0.01 Al _0.98 P _0.98 As _0.02 Cladding layer (1
μm) and a p-type GaP cap layer (100 nm) were continuously grown. The thicknesses of the guide layer and the active layer were designed so that crystal defects would not occur.

The grown wafer is provided with a current confinement layer made of a silicon nitride film, a p-type electrode and an n-type electrode, and is then grown to 300 μm.
It was cleaved into m squares and made into chips. Since the clad layer was exposed on the cleavage plane, it was coated with a silicon nitride film in order to prevent deliquescence. When a current was injected into the semiconductor laser device manufactured in this manner, yellow laser light was oscillated at room temperature.

[0015]

According to the present invention, In _1-xy Ga _x Al _y
P _1-z As _z (where x, y, and z are 0 ≦ x ≦ 1, 0
≦ y ≦ 1,0.5 ≦ x + is in the range of y ≦ 1,0 ≦ z ≦ 0.5) was used as a clad _{layer, In 1-xy Ga x Al} y P 1-z
As _z (where x, y, and z are 0 ≦ x ≦ 1, 0 ≦ y
≦ 1, 0 ≦ x + y ≦ 1, 0 ≦ z ≦ 1) is provided adjacent to the strained active layer.
A semiconductor laser device was obtained which oscillated by current injection even at room temperature.

[Brief description of drawings]

FIG. 1 is a bandgap diagram of an example near the strained active layer of the present invention.

FIG. 2 is a structural cross-sectional view of the semiconductor laser device according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Buffer layer 3, 7 ... Cladding layer 4, 6 ... Guide layer 5 ... Strained superlattice active layer 8 ... Cap layer 9 ... Current constriction layer 10 ... P-type electrode 11 ... N-type electrode

Claims (5)

[Claims] 1. A strained active layer and In _1-xy Ga _x A on a substrate.
l _y P _1-z As _z (where x, y, and z are 0 ≦ x ≦
1, 0 ≦ y ≦ 1, 0.5 ≦ x + y ≦ 1, 0 ≦ z ≦ 0.5
In the semiconductor laser device having a clad layer composed of
_{1-xy Ga x Al y P} 1-z As z ( although values of x, y, z are, 0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ x + y ≦ 1,0 ≦ z
The semiconductor laser device is characterized in that a guide layer made of (≦ 1) is arranged. 2. The semiconductor laser device according to claim 1, wherein the mixed crystal composition x, y or z of the guide layer has a value that continuously changes in the film thickness direction. 3. The semiconductor laser device according to claim 1, wherein the substrate is Si. 4. A semiconductor laser device according to claim 1, wherein the substrate is GaP. 5. The semiconductor laser device according to claim 1, wherein the guide layer is Al _y Ga _1-y P (where y is in the range of 0 ≦ y ≦ 1 and is continuous in the film thickness direction). A semiconductor laser device.