JPS61119092A - Manufacture of semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain the stripe structure having a strong effect of current narrowing by forming the multilayer thin films including a double hetero structure on a substrate in a manner a thickness of the uppermost layer of the multilayer thin films is thin on the projecting part and is thick in other parts and then a conductive type of the uppermost layer of the multilayer thin films becomes the same as the substrate on the projecting part. CONSTITUTION:On an N type GaAs substrate 1, stripe-form projections of a normal mesa are arranged in parallel to <011> direction by photolithography. By an MOCVD method, an N type GaAs buffer layer 2 is grown to 1mum in a flat part by crystal growth and an N type Ga1-xAlxAs clad layer 3 to 1.5mum, an N type Ga1-yAlyAs active layer 4 (0<=y<=x) to 0.07mum, a P type Ga1-xAlxAs clad layer 5 to 1.2mum, and an N type GaAs current blocking layer 6 to level the surface are grown. From the surface 10 of the N type GaAs current blocking layer 6, diffusion of Zn is made without a mask. By making a depth of diffusion of Zn slightly deeper than (d) in the drawing, the front 7 of a Zn diffusion region 8 can enter only in the part above the projection of the P type Ga1-xAlxAs clad layer 5.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a method for manufacturing semiconductor laser devices, whose applications have been rapidly expanding in recent years and demand is increasing as light sources for various electronic devices and optical devices. .

Conventional Structures and Problems The important performances required of semiconductor lasers as coherent light sources for electronic and optical equipment include low current operation and single-transverse mode oscillation. In order to achieve these, it is necessary to suppress the spread of the current flowing through the laser element so as to concentrate it near the active region where the laser light propagates, and to confine the light. A semiconductor laser having such a structure is usually called a stripe type semiconductor laser.

A relatively simple striping method uses only current constriction. Specifically, laser-type semiconductor lasers have been subjected to proton irradiation, Zn diffusion has been performed, insulating films such as oxide films have been formed, and current constriction regions have been created inside by crystal growth, etc. Examples include things that are attached. However, each of these methods has significant drawbacks. When proton irradiation is applied, some crystals in each layer of the semiconductor laser are damaged during the proton irradiation, which may impair the characteristics of the semiconductor laser. In the case of Zn diffusion type, 7
Zn diffusion is often carried out at high temperatures such as 00 to 850'C, and there is a problem in that dopants such as Zn move in the crystal, making it difficult to form a p/n junction as designed. The method using an insulating film such as an oxide film has a weaker current narrowing effect in the fabricated semiconductor laser than the above two methods.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a method for manufacturing a semiconductor laser device that can easily form a strong current confinement stripe structure.

Structure of the Invention In order to achieve this object, the method for manufacturing a semiconductor laser device of the present invention employs a metal organic vapor phase epitaxial growth method (MO
CVD method) is used to deposit a multilayer thin film containing a double heterostructure on a substrate having striped protrusions so that the thickness of the top layer of the multilayer thin film is thinner on the protrusions and thicker in other parts. Then, the uppermost layer of the multilayer thin film is formed using dopant diffusion, ion implantation, etc. so that the conductivity type of the uppermost layer is the same as that of the substrate on the convex portion.

This configuration forms a stripe structure with a strong current confinement effect, resulting in single-transverse mode oscillation.

A semiconductor laser device with low threshold operation can be realized relatively easily.

DESCRIPTION OF EMBODIMENTS An embodiment of the method for manufacturing a semiconductor laser device of the present invention will be specifically described with reference to the drawings.

- As an example, use n-type GaAg for the substrate. 1st
As shown in the figure, a width of 5 μm is formed on an n-type GaAs substrate 1 by photolithography in parallel to the <011> direction.

A mesa striped convex portion with a height of 1.6 μm is provided.

Next, as shown in Figure 2, an n-type G
a A tr buffer layer 2 is 1μ-n type Ga in the flat part
1-tAl, As cladding layer 3 is 1.5 μm
, G a 1++ y A Z y As active layer 4 (
0≦y<x) to 0.07ttm, p-type Ga 1-
x AZ The growth conditions are, for example, a growth rate of 2 μm/hour, a growth temperature of 770'C, a total gas flow rate of 5 t/';
The molar ratio of Group I elements to Group II elements is 40.

Under these growth conditions, crystal growth is achieved while preserving almost the uneven shape of the substrate, which is characteristic of MOCVD.

Thereafter, as shown in FIG. 2, Zn is diffused from the surface 10 of the n-type GaAs current blocking layer 6 without a mask.

At this time, since the crystal growth layer at the center of the convex part is thinner than the parts other than the convex part, by setting the Zn diffusion depth a little larger than d in FIG. 2, the front 7 of the Zn diffusion region 8 is made of p-type Ga1
- Air can be inserted only into the upper part of the convex part of the AtxAs cladding layer 6. The thickness of the shrimp layer grown by MOCV D method is
It is within 6% and has good reproducibility (Zn diffusion can be performed).

As a result, the Zn diffusion region of the n-type Ga As layer becomes p-type Ga As, and p-type Ga 1. ,, x A
A current narrowing stripe structure having a width W is formed above the convex portion of the Z x As cladding layer 3 . Shrimp growth side 1o
On the p-side one-mic electrode, on the n-type GaAs substrate 9
When a current was applied to the side ohmic electrode, the distance was 40 m.
A semiconductor laser device that oscillates in a single transverse mode with a threshold value of approximately A was obtained.

In addition, in this example, G a As system, G a
Although the A tA s semiconductor laser has been described, the In
The present invention can also be applied to semiconductor laser devices made of compound semiconductors containing P-based and other multi-component mixed crystal systems.

Effects of the Invention The method for manufacturing a semiconductor laser device of the present invention provides a semiconductor laser device that oscillates in a single transverse mode at a low threshold value, and has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a substrate having unevenness constituting the semiconductor laser device described in this embodiment, and FIG. 2 is a diagram showing an example of a semiconductor laser device manufactured using the manufacturing method of the present invention. 1...N-type GaAs substrate, 2...
・N-type GaAs buffer layer, 3...n-type GaAtAs cladding layer, 4...GaA7
As active layer, 6... p-type Ga A tA
s cladding layer, 6...n-type GaAs current blocking layer, 7...Zn diffusion front, 8...
...Znn diffusion pear-shaped region 9...n-side electrode production surface, 10...p antistatic, electrode production surface, d...
Diffusion depth, W... Stripe width.

Claims (1)

[Claims] Using metal-organic vapor phase epitaxial growth, a multilayer thin film containing a double heterostructure is formed on a substrate having striped convex portions, and the thickness of the top layer of the multilayer thin film is thinner on the convex portions and thinner on other portions. The multilayer thin film is formed to be thick, and then impurities are introduced so that the conductivity type of the uppermost layer of the multilayer thin film is opposite to that of the substrate on the convex portions and is the same as that of the substrate on other portions. A method for manufacturing a semiconductor laser device.