JPS6174383A - Semiconductor laser array device and manufacture thereof - Google Patents

Abstract

PURPOSE:To realize a laser array device equipped with a stable oscillation wavelength by a method wherein a stripe-shaped mesa is produced, on a multilayer thin film, with its sides inclined both inside and outside and a multilayer thin film including a P-N junction is formed on the inclined sides of the mesa. CONSTITUTION:On a GaAs substrate 10, a buffer layer 11, clad layer 12, activation layer 13, and clad layer 14 are formed into a multilayer thin film, whereon a resist mask is formed. The resist mask is used for the etching of the clad layer 14, which is the topmost layer of the multilayer thin film, whereby a mesa is formed, equipped with two inclined sides A, B. Next, a current-stopping layer 16 is formed on the two inclined sides A, B of the mesa, which is followed by the formation of another current-stopping layer 16 and a contact layer 17 on top of the mesa. In this design, the length may be made long enough, along the direction parallel to the resonator surface in the activation region 20 just under the mesa and the semiconductor junction surface, for the realization of a high-integration laser array device free of scattering of performance characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is applicable to various electronic devices as a coherent light source or as a high output, high density, high brightness light source.

The present invention relates to a semiconductor laser array device used in optical 8iJa and a method for manufacturing the same.

(Conventional Structure and its Problems) One of the important uses of semiconductor laser array devices is as a high-output, highly integrated light source. This requires that one chip has a large number of laser oscillation regions, each of which is close to each other, and whose characteristics such as the oscillation wavelength and phase of the laser light are uniform. Laser array devices manufactured using the conventional liquid phase epitaxial growth method use stripes formed on the substrate, Zn diffusion on the grown epitaxial layer, proton irradiation, and stripes formed by an insulating film, so that the chip surface occupied by a unit laser oscillation area is When a large number of oscillation regions are integrated into a chip of an appropriate size, the degree of integration is low, and since it is manufactured using liquid phase epitaxial and growth methods, the oscillation wavelength of the laser light There is a drawback that variations in characteristics such as variations become large.

(Object of the Invention) In view of the above-mentioned drawbacks, the present invention provides a semiconductor laser array device having a structure in which there is little variation in characteristics such as the oscillation wavelength of laser light and can integrate laser oscillation regions on a chip with a large degree of integration, and its manufacture. The purpose is to provide a method.

(Structure of the Invention) In order to achieve this object, the semiconductor laser array device of the present invention provides a multilayer thin film including a double heterostructure on a semiconductor substrate, and a flat end surface and its adjacent side surface are formed on the multilayer thin film. The inner angle formed by the protrusion is an obtuse angle, and at least one side surface other than the adjacent side surface has a striped convex portion having an inner angle of 90° or less forming the flat end surface, and both side surfaces of the convex portion are p-
Surrounded by a multilayer thin film including an n-junction, the length of the active layer immediately below the convex portion in a direction parallel to the resonator plane and the semiconductor junction plane is sufficient to have two oscillation regions. ing. With this configuration, there is little variation in characteristics and it is possible to integrate the laser oscillation region with a relatively large degree of integration.

(Description of Embodiment) The semiconductor laser array device of the present invention will be specifically described using one embodiment.

An n-type GaAs substrate 10 (carrier concentration: 10''-a) is used as a semiconductor substrate.Metalorganic vapor phase epitaxial growth (hereinafter referred to as MOCVD) is performed on this substrate.

), as shown in FIG.
The n-type Ga1-xAidxAs cladding layer 12 is 1.5
p m, Ga1-, A et al. As active layer 13 (O≦y(x;
y<z) is 0.1 μm, p-type Ga1-zAIIzAs
The cladding layer 14 was grown L5ptrr epitaxially. An example of crystal growth conditions using the MOCVD method at this time is shown below. The growth rate was 2 μm/hour, the growth temperature was 770° C., the total gas flow rate was 512/min, and the molar ratio of group Ⅰ elements to group Ⅰ elements was 40. Then, as shown in Figure 1, p
The pitch is 300 on the type Ga1-zizAs cladding layer 14.
μm, [leave photoresist mask 15 at 20 μm,
It is processed into the shape shown in FIG. 2 by chemical etching. In Figure 2, p-type Ga□-2AQzAs cladding layer 1
The film thickness of No. 4 is set such that the thick part at the center is 1.5 μm and the thin part around 1 is 0.3 μm. Further, the heights d and jd2 of the ridge in FIG. 2 were set to 0.2 μI and 1.0 μI, respectively. 1 is the width of the photoresist mask, and e2 is the width of the mesa ridge portion.

The reason why the Ga□-1A or As active layer 13 is not exposed is to avoid damage during etching or crystal growth. After removing the photoresist and cleaning the surface, apply M again.
By OCVD method, as shown in Fig. 3, n+-GaA
The s current blocking layer 16 (carrier concentration: 10"cn-") was epitaxially grown to a thickness of 1 .mu.m under the above-mentioned growth conditions, and the P"-GaAs contact layer 17 (carrier concentration: 5.times.10"an-3) was grown epitaxially to a thickness of 1.mu.m. Grow to a thickness of 0 μm.

After surface cleaning, the surface of the n-type GaAs substrate IO and P+
-Ohmic electrodes 18 and 19 were formed on the surface of the GaAs contact layer 17, respectively, resulting in the structure shown in FIG.

When a current is passed through this structure, no current flows through the n''-GaAs current blocking layer 16 on the striped convex portions.

However, current flows from both sides of this layer, p-type Ga,
It flows into the active region 20 shown in FIG. 3 through the striped convex portions of the zA1zAs cladding layer 14.

At this time, if the cline dW between adjacent current injection stripes shown in FIG.
Two laser oscillation regions are formed. The two laser oscillation regions oscillated almost simultaneously near the threshold of 70 mA, and stable single-transverse mode oscillation was obtained in each region. In addition,
The reason why the injected current is narrowed to the striped convex portion is because
In FIG. 3, when the p-side electrode 18 is set to + and the n-side electrode 19 is set to -, the p-type GaX-2izAs cladding layer 14 and the n''-Ga
This is because the p-n junction at the interface of the As current blocker J'516 becomes reverse biased and acts as a current blocker. Further, in this embodiment, the n''-GaAs current blocking layer 16 is Ga1
-, AI! Since the forbidden band width is narrower than that of the As active layer 13, it absorbs light, and as a result, the light is also confined in the striped convex portions of the p-type Ga knee zAilzAs cladding 514.

By the way, in a typical laser array device, only one laser oscillation region can be obtained in the active region directly under one striped convex portion. This configuration becomes a basic unit and forms a laser array. However, in the case of the present invention, unlike the above, there are two laser oscillation regions, so if a laser array with the same number of laser oscillation regions is manufactured, the volume of the chip becomes about half, and miniaturization is possible.

Note that the material forming the p-n junction surface of the present invention is GaAs.
Materials other than Ga1As-based and Ga1As-based may also be used.

In addition, in the two embodiments, GaAs-based and GaAlAs-based semiconductor lasers have been described, but the present invention can be similarly applied to semiconductor lasers made of compound semiconductors including InP-based and other multi-component mixed crystal systems. It is. Furthermore, as the conductive substrate, a p-type substrate or a semi-insulating substrate may be used, and the crystal growth method may include other material supply rate-limiting crystal growth methods, such as molecular beam epitaxial growth (
(usually called MBE method) may also be used.

(Effects of the Invention) The semiconductor laser array device of the present invention has a 4A structure that allows highly integrated lasers that oscillate in a single transverse mode with low threshold operation, and its practical effects are remarkable. .

[Brief explanation of drawings]

1 to 3 are diagrams showing the manufacturing process of a semiconductor laser array device according to an embodiment of the present invention. 10- n-type GaAs substrate, 11- n''-GaAs buffer layer, 12... n-type Ga□-, AlxAs cladding layer, 13... Ga, -, AN, As active M(0
≦y<x;y<z), 14...p-type Ga□-, Alx
As cladding layer, 15... photoresist mask,
16...n"-GaAs current blocking layer, 17-p"-
GaAs contact layer, 18 ・p side piece-mic electrode,
19... n-side ohmic electrode, 20... active region,
Re: Width of photoresist mask, e2: Width of mesa-shaped ridge portion, do. d2... Height of ridge, d,... Distance between adjacent current injection stripes. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A multilayer thin film including a double heterostructure is provided on a semiconductor substrate, and an internal angle formed between a flat end surface and an adjacent side surface thereof is an obtuse angle, and at least one side surface other than the adjacent side surface is formed at the tip end. A striped convex portion having an internal angle of 90° or less with the flat surface is formed, and both side surfaces of the convex portion are p
- The length of the active layer in the direction parallel to the resonator plane and the semiconductor junction plane, which is surrounded by a multilayer thin film including an n-junction and directly under the convex portion, is long enough to have two oscillation regions. A semiconductor laser array device characterized by the following. (2) forming a multilayer thin film having striped convexities on the surface and including a double heterostructure on a semiconductor substrate; 1. A method for manufacturing a semiconductor laser array device, comprising the step of surrounding the semiconductor laser array device with a multilayer thin film including a pn junction using a line epitaxial growth method.