JPS60235486A - Semiconductor laser device and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain narrow striped structure easily on the inside by forming a thin-film layer having conductivity reverse to a conductive substrate on the substrate with an inverted mesa-shaped stepped section and shaping multilayer thin- films containing double hetero-structure on the thin-film layer. CONSTITUTION:A stepped section 2 is formed on a P type GaAs substrate 1. The section of the stepped section 2 takes an inverted mesa shape. The growing surface of the substrate is washed by an organic solvent, etc., and a crystal is grown. A clad layer 4, an active layer 5, a clad layer 6 and an N type GaAs layer 7 are formed on the stepped section after an N-GaAs layer 3 is grown, and growth is completed when the growing surface is cladded. When electrodes are manufactured to both the P type GaAs substrate 1 and the N type GaAs layer 7 and currents are flowed, currents are injected in width (d), and current constriction is realized. It is because the N type GaAs layer 3 shapes a P/N junction together with the clad layer 4 and the P/N junction is reverse-biassed on the injection of currents.

Description

DETAILED DESCRIPTION OF THE INVENTION The industrial field of application is -fr semiconductor laser devices and semiconductor laser devices whose applications are rapidly expanding as light sources for various layer electronic equipment and electrical equipment for chemical production and production. The present invention relates to a manufacturing method thereof.

The configuration of the conventional example and its problems The important performance required of a semiconductor laser as a coherent light source for electronic and optical equipment is oscillation in a single spot of 1":) Vc1, that is, single-transverse mode oscillation. To achieve this, it is necessary to suppress the spread of the current flowing in the semiconductor laser device near the active region and to confine the light.

Such a semiconductor laser is generally not called a stripe type semiconductor laser.

A relatively simple method of forming a stripe is a method using only current narrowing. Specifically, examples include those in which a vertical type semiconductor laser is subjected to proton irradiation, those in which a Zn pattern is spread, and those in which an insulating film such as an oxide film is formed. Each of these methods has significant drawbacks. When irradiated with protons, some of the crystals in the calyx laser may be damaged during croton irradiation, which may impair the characteristics of the semiconductor laser. For Zn expansion type, 70()-850℃
Processing is often carried out at such high temperatures that dopant such as Zn moves in the crystal, making it possible to form stripes, but it is difficult to form narrow stripes. The method using an insulating film such as an oxide film has a disadvantage in that the effect of narrowing the current in the manufactured semiconductor laser is weaker than the two methods described in @.

Purpose of the Invention In view of the drawback L, the present invention provides a current limiting layer on a conductive substrate E, and a multilayer thin film including a double heterostructure is provided on the current limiting layer, so that the current distribution can be made internal via the current limiting layer. The object of the present invention is to provide a semiconductor laser device in which a narrow stripe structure can be easily obtained, and a method for manufacturing the same.

Structure of the Invention In order to achieve the above object, the semiconductor laser device of the present invention is provided by forming a thin film layer having conductivity opposite to that of the front substrate on a conductive substrate which forms an inverted mesa-like step, and It has a structure in which a multilayer thin film including a double heterostructure is formed in the thin film layer, and with this structure, it is possible to have a current narrowing stripe inside, and it is possible to create a semiconductor laser with single-transverse mode oscillation and low threshold operation. The device can be realized.

DESCRIPTION OF EMBODIMENTS An embodiment of the semiconductor laser device of the present invention will be described below with reference to the drawings. In Figures 1 and 2 - for example,
A case where a P-type GaAs substrate is used as a semiconductor substrate will be explained. <011. > Parallel to the direction (2 steps)
) will be established. At this time, the cross-sectional shape of the step (2) becomes an inverted mesa shape as shown in FIG. Next, using the MBE method, the n-type GaAs(3) (t-P rear concentration I
x 10"cyn", growth rate 1μ Utsu)
It grows to about μm. As shown in FIG. 1, there is a region near the inverted mesa-shaped step (2) [d] where the growth hardly occurs.

After cleaning the surface of the grown substrate with an organic solvent, LP
Crystal growth is performed by E method. Growth was performed at a humidity of 850°C, a supersaturation level of 7°C, and a cooling rate of 0.5°C/min. After growing the n-GaAs layer (3) shown in Fig. 1, a ρ-type Ga, y, At
) (0<, y<x), n-type Ga, )(At)(As
A cladding layer t6Ln type GaAs layer (7) is formed, and the growth is finished when the growth surface becomes a cladding. When electrodes are made on both the P-type GaAs substrate (1) and the n-type GaAs layer (7) and a current is applied, the flow from the P-type GaAs substrate (1) to the P-type Ga, -XAlxAs cladding layer (4) is as follows.
A current is injected with a width d shown in FIG. 2, and current narrowing is realized. This means that the n-type GaAs layer (3) is P'l
Gal-xA7? ) (As ri5 ``J t' Nj
(4) (!: When forming a p/n junction and injecting current,
This is because the p/n junction becomes reverse biased. As a result, a low threshold semiconductor laser device with a threshold current of 20 mA at d=2 μm could not be obtained. As a result, single-transverse mode oscillation was also realized at the same time.

In this example, GaAs-based, GaAl! Although the As-based semiconductor has been described, the present invention can be similarly applied to semiconductor lasers made of compound semiconductors including InP threads and other multi-component mixed crystal threads.

Effects of the Invention According to the present invention, it is possible to perform point E-hand control on a single tank with a low threshold value. - It is said to be used in winter, and its practical effects are remarkable.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a cross-sectional view showing a growth shape on a stepped substrate by the MBE method, and FIG. 2 is a cross-sectional configuration diagram showing a semiconductor laser according to the present invention. (1) -p-type GaAs substrate, (2) ... step, (
3) -n-type GaAs current limiting layer, (4) -P-type GaA
l! As cladding layer, (5) -GaAJ! As active layer, (6) -n-type GaAlAs cladding layer, (7) -
Yoshihiro Morimoto, n-type GaAs layer agent

Claims (1)

[Claims] 1. A thin film layer having conductivity opposite to that of the substrate formed on a conductive substrate having a step, except for a region near the intersection of the lower surface of the step and the sloped surface of the step, and the substrate and A semiconductor laser device having a multilayer thin film including a double heave zero structure formed on top of the thin film layer. 2. A thin film layer having a conductivity opposite to that of the substrate is coated on a conductive substrate t having a step where the angle between the surface of the lower part of the step and the surface of the sloped part is more than 90 degrees using the MBE method (molecular beam technique). A method for manufacturing a semiconductor laser device, wherein a multilayer thin film including a double heave structure is formed on the thin film layer by an LPE method (liquid phase epitaxial method).