JPS6086888A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To form a steep multilayer structure and a striped structure for strong current constriction on an interface and to improve the laser characteristics and the reliability of a semiconductor laser by a method wherein a crystal-growth is performed on a multilayer thin film including a double-hetero structure while a local heating means is applied. CONSTITUTION:A double-hetero structure is grown by successively forming an N type AlXGa1-XAs layer 11, an AlYGa1-YAs layer 12 (0<=Y<X) and a P type AlXGa1-XAs layer 13 on an N type GaAs single crystal substrate 10 as a single crystal, and P type GaAs layers 25 are grown on the double-hetero structure, whereon laser beams are stricken in a stripe shape at a pitch of (1), while a local heating is performed. The neighborhood of a place, where laser beams are striking, is converted into a GaAs single crystal layer 24, while places, where laser beams are not striking, are converted into GaAs polycrystaline layers 25. As a result, a current-constriction is performed at the place of the width of a stripe part 16, thereby enabling to generate a single transverse-mode oscillation at a lower threshold value.

Description

[Detailed description of the invention] Industrial applications The present invention is a digital audio disc.

The present invention relates to a semiconductor laser device used as a coherent light source for video disks and other devices, as well as a light source for various electronic devices.

Conventional configurations and their problems One of the requirements for semiconductor lasers as light sources for electronic devices is oscillation in a single spot, that is, single-spot oscillation.
There is transverse mode oscillation. To achieve this, it is necessary to confine light and current near the active region. Regarding light confinement, optical amplification can be achieved by sandwiching the active layer with a double heterostructure and creating a refractive index difference in the direction perpendicular to the active layer, or by allowing a current to flow through a part of the active layer. There is a method to confine the rate by giving it a distribution in the active layer.

Concerning current confinement and confinement of carriers, the active JWt'r is sandwiched in the double heterostructure, and the electron energy node in the semiconductor is confined by the structure of the sandwich, and in the direction perpendicular to the double heterostructure, the active JWt'r is trapped. A common method is to provide a striped current constriction region so that current flows only near the region.

FIG. 1 shows the entirety of a typical conventional blade structure. In these figures, 10 is n+-G a A s
Substrate, 11 is n Al x Ga 1 x As layer, 12 is AI Ga As (o<y<”) layer, 1si
dp-71-7 AI GaAs layer, 14 is p-GaAs layer, 16 is active x1-x active region, 16 is stripe part, 17 is n-GaA
g layer, 21 is a high resistance region irradiated with protons, 22
is a Zn diffusion region, and 23 is a S z 02 film.

A is a laser that forms a stripe portion 16 by irradiating protons from above the p-GaAs cap layer 14. b, by growing an n-GaAs layer 17 on the p-AlxGa1-xAsAs layer 3 and completely diffusing Zn from above the n-GaAs layer 17, thereby forming an n-GaAs layer 17.
A stripe portion 16 for current injection was formed therein. Znn
There is a diffused stripe structure laser.

C is a laser in which a stripe 16 for current injection is formed by providing an insulating film 23 such as an io2 film on the top layer 4 of the p-GaAs cap layer.

In each case, the stripe portion 16 limits the area where current flows, reduces the oscillation threshold of the semiconductor laser, and also reduces the oscillation threshold of the active layer A y Ga in FIG. 1.
1-y As s layer (0≦y(x) oscillation region in 12 (
Hereinafter, this will be referred to as the active region 16. )'fr: Due to its shape effect, high-order transverse mode oscillation is completely suppressed and single-transverse mode oscillation is realized.

However, the method for producing the striped structure described above has the following drawbacks.

1 In FIG. 1a, ions such as protons are accelerated by an electromagnetic field and irradiated onto a fabricated double heterostructure semiconductor wafer. At this time, the irradiated area of the semiconductor wafer is damaged by the passage of the accelerated ions. Moreover, near the active region or near the proton irradiation region directly above the active region, the Ga As layer,
The crystal of the GaAIAs layer is damaged, impairing the electrical characteristics, optical characteristics, reliability, etc. of the semiconductor laser. In order to avoid this, it is necessary to perform annealing at a high temperature after proton irradiation, which not only increases the number of steps but also causes the presence of dopants with high thermal diffusion coefficients such as Zn in the annealed layer. As a result, it becomes difficult to obtain a multilayer structure with good controllability of the moving carrier concentration.

2 Figure 1 b-r: Zn diffusion is carried out at high temperature (7ooC ~
a5ot, ), and the dopant in each layer is also diffused, causing the p/” junction interface to shift from the designed position, or p
/ ``Joints become difficult to form according to design.

3. In FIG. 1C, there is a problem that the active region 16 in the AlyGa 1yAs active layer 12 is wider than in the laser having the two-wave structure of FIGS. 1a and 1b. Compared to Figure 1 a and b, the structure in Figure 1 C is
This is because the current constriction by the stripes 16 is weak.

4 The striped structure lasers shown in FIGS. 1a to 1c are fabricated using separate equipment for the crystal growth of the multilayer thin film containing the double heterostructure and the process for providing the striped structure for current confinement. It is not possible to produce both at once with one device.

OBJECTS OF THE INVENTION In view of the above drawbacks, the present invention provides a method for manufacturing a semiconductor laser device in which the carrier concentration is well controlled and a steep multilayer structure and a strong current confining stripe structure are formed at the interface in one crystal growth. It is something to do.

Structure of the Invention In order to achieve this object, the method for manufacturing a semiconductor laser device of the present invention involves growing a multilayer thin film crystal including a double heterostructure while using local heating means, and forming a part of the crystal growth layer into a single crystal. In some areas, the rest consists of entirely fabricating a thin film, which is a polycrystalline layer.

This structure does not damage the double hetero-occupied structure and its crystal layer, and the single crystal region, which is a part of the polycrystalline thin film, forms a good current narrowing stripe. It is possible to manufacture a semiconductor laser device fl' which can be fabricated up to a stripe structure and which oscillates in a single transverse mode at a low threshold value.

DESCRIPTION OF EMBODIMENTS FIG. 2 shows an example of a semiconductor laser device manufactured according to the present invention. The manufacturing method of the present invention will be specifically explained using Examples.

In FIG. 2, an n-type GaAs single crystal substrate 10 is epitaxially grown, that is, by MOCVD (metal organic chemical vapor deposition) or MBE (molecular beam epitaxial method), sequentially --A I! G a 1-
xAs layer 11, AI, Ga1-yAs layer 12 (.

≦y<x), p-AI, Ga1. Each As layer 13 is grown as a single crystal (in the case of a p-type GaAs single crystal substrate 10, p-AlxGa1-
) cAB layer 11 , AlyGa, , Aa layer 12 (0
≦y×χ) −toA ] x Ga 1x A s layer 1
3) Then, the substrate temperature yMOcV
The temperature is lowered to 400C in the case of the D method and 300C in the case of the MBE method, and a laser beam or electron beam is applied to the double heterostructure in stripes at a pitch l as shown in Figure 3 for local heating. While carrying out these steps, the p-GaAs layer 26 is grown as a crystal. (In the case of p-type substrate 1, n - Ga
The As layer 26 is grown. ) The local heating means narrows the beam diameter to a spot with a diameter of 6 to 10 μm and scans it at high speed, raising the temperature of the substrate in that area by 100 C to 2 OOCW, and the laser beam or electron beam is applied in a 3-degree stripe pattern. As shown in Figure 2, the area around the G
This becomes an aAs single crystal region 24, and the uncontacted area becomes a GaAs+ polycrystalline layer 26. As a result, the specific resistance of the polycrystalline layer 25 is 4
Since the current becomes larger by several orders of magnitude, the current is narrowed by the width of the stripe portion 160, and a striped structure laser that emits light in a single transverse mode with a low threshold value is obtained.

In addition, in this example, Ga As system-Ga AI
Although the description has been made regarding the As passive conductor laser, the present invention can be similarly applied to semiconductor lasers made of compound semiconductors including Iup systems and other multi-component mixed crystal systems.

In addition to the effects of the invention, according to the present invention, a striped structure laser that emits light in a single transverse mode can be manufactured.

0 The method for manufacturing a semiconductor laser device of the present invention includes S 1
A current narrowing stripe equivalent to that of a proton irradiation type stripe structure laser can be provided, a low threshold laser can be obtained, and the epitaxial layer grown on the substrate will not be damaged, improving the characteristics and reliability of the laser. 3. Compared to the conventional stripe structure, no process is required just to provide the stripe, and a multilayer thin film for semiconductor laser fabrication including a double heterostructure and a stripe structure can be created in one crystal growth. It is easy to form.

It has great practical effects.

2 is a cross-sectional view of a semiconductor laser device manufactured by the method of manufacturing a semiconductor laser device of the present invention, and FIG. 3 illustrates a method of forming a stripe structure using local heating means in the same method. This is a diagram for

10---n-GaAs substrate (p-GaAs substrate),
11...n-A18Ga1-xAB layer (p A
l x G a 1x'' layer), layer), 14-...
p-GaAs layer (n-GaAs layer), 16...
Active region, 16...stripe or stripe width, 17...n-GaAs layer, 21...
・High resistance region irradiated with protons, 22...Z
n diffusion region, 23...S z 02 film, 24.
...Ga As single crystal region, 26...
・G a As polycrystalline layer, 31... Part where single crystal is grown in a stripe shape, 32...
Semiconductor sea urchin grown epitaxially on a substrate...

Name of agent: Patent attorney Toshio Nakao and one other person Ix
Figure 1

Claims (1)

[Claims] Crystal growth is performed on a multilayer thin film containing a double heterostructure while locally irradiating a laser beam or an electron beam, and a single crystal thin film is formed in the locally irradiated area and a polycrystalline thin film is formed in the area that is not locally heated. A method of manufacturing a semiconductor laser device, characterized by: