JPS6063976A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To realize the titled device of high output by basic lateral mode oscillation by a method wherein each layer including an active layer is formed on a substrate with two parallel ridges formed, and the shape of a groove between ridges is made a dove tail form having depths varying discontinuously. CONSTITUTION:The two ridges are formed by etching on the plane (100) of an N type GaAs substrate 1 in the direction of <011>. An N type Ga0.57Al0.43As clad layer 2 of the first layer, a non-doped Ga0.92Al0.08As active layer 3 of the second layer, a P type Ga0.57Al0.43As clad layer 4 of the third layer, and an N type GaAs layer 5 of the forth layer are successively grown on the surface of the substrate where the ridges have been provided. Next, Zn is selectively diffused from the grown surface to the upper part of the substrate groove in stripe form, so that the diffusion front may reach the third layer. A metal for the P-side electrode is evaporated and alloyed, and the P-side ohmic electrode 6 is then formed. On the other hand, a metal for the N type electrode is evaporated on the substrate side and alloyed, and the N-side ohmic electrode 7 is then formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor laser device.The structure of a conventional example and its problems In recent years, semiconductor laser devices have been used for reading, reading, and erasing information from optical disk files, etc. Alternatively, for applications such as laser printers, a semiconductor laser with high output and 1.1 transverse mode oscillation is required. One very effective means for stabilizing the transverse mode is to provide Wik on the substrate.

As an example of such a semiconductor laser device, FIG.
P (Channeled 5ubstrate P
larar) Indicates what is called a laser. The structure of this laser is that a groove is provided on an n-type substrate 1, and on the second side, an n-type cladding layer 2, an undoped active layer 3, and a p-type cladding layer 4.
, the entire n-type GaAs layer 6 is continuously grown, and then p-type impurities are selectively diffused from the surface of the grown layer from just above the trench to the p-type rad layer to form a diffusion region 8. Note that 6.7 is for the electrode. In this structure, which is a metal film, there is an effective refractive index difference between the outside and inside of the groove for the light that has leaked from the active layer 3 to the first cladding layer 2. It would be possible to achieve fundamental transverse mode oscillation by being confined inside the groove, but in order to realize high output power of the conductor laser,
An effective method is to reduce the total thickness of the active layer so that all the light passes through the cladding layer, thereby increasing the entire light emitting area.

However, in the laser having the structure shown in FIG. 1, it is very difficult to form a very thin active layer over the groove as long as the liquid phase epitaxial method is used. Also, a shown in FIG.
In sp lasers, the shape of the groove is a trapezoid with a wide top, but this shape is disadvantageous for achieving high output because it is necessary to obtain a groove deep enough to confine light. The slopes of the groove (between a-b and between c-c1) become longer, and the absorption of light into the substrate there increases.As a result, even if the active layer is made thinner, the light will not reach the cladding layer to a large extent. μ
j) Even if it is possible to extract the liquid, the loss due to the shape of the groove is large as described above, making it difficult to obtain an external differential quantum efficiency of 1h'1. The purpose of
- Provides a complete semiconductor laser device capable of growing a very thin active layer and stably confining light leaking from the active layer with minimal loss +/= T seconds. Structure of the Invention In order to achieve all of the above objects, the semiconductor laser device of the present invention is such that each layer including the active layer is formed on a moving plate on which two parallel ridges are formed, and the shape of the groove between the ridges is Description of an embodiment characterized by a dovetail shape in which the depth changes discontinuously An embodiment of the present invention will be described below with reference to all the drawings. Two ridges 7 having a height of 1.5 μm and a width of 20 μm are formed by full etching in the <011> direction. With such a substrate surface and etching direction, a groove having an inverted mesa-shaped edge as shown in FIG. 2(a) is formed on the substrate. The width of the bottom part between the ridges is 6μ7×1. Jl with a ridge (No. 11 n-type CT"0.57 A on plate surface 1-
10.45 As crack layer 2 on top of ridge gB about 0.4μ) 2nd layer non-dozo Gap, g2Al
oo6ASμ2no1, 4th layer n-type (raAs5'i about 0
．． Continuous growth was performed to a thickness of 5 μl (Figure 2 (b)
) Formation I (When supercooling is carried out at 5°C from a constant temperature of 790°C, the shape of the 11 parts changes to a dovetail shape as shown in Figure 2 (b) due to meltback, and grooves are formed.) The width of the second part is about 6 μm. Then, from the growth surface to the top of the substrate groove, 1L is formed in a stripe shape.
The selective diffusion of li lead is carried out so that the diffusion front reaches the third layer p-type Gao5□A1o43As cladding layer.After that, metal for the p-side electrode is evaporated and alloying is performed to form the p-side ohmic electrode 6. Finally, on the substrate side, the metal for the n-type electrode is completely vapor-deposited, and the alloy processing is performed to completely form the n-side ohmic electrode T (Fig. 2 (C)). The +1i/+ operation of the semiconductor laser device constructed as described above, which is completed by mounting it on a Si block, will be explained below. Approximately 90 of the light generated in the first cladding layer 2 is confined in the grooves between the ridges. Then, the slope part where all the light is absorbed (e - f in Fig. 2 (C)
Since it is possible to shorten the gap (between 1 and 1 and between .

In fact, in the semiconductor laser of this embodiment, the noise (tree bi′I)
Moh' 4fA f, threshold current about 6Q ill
A, high-output laser gold with an external f'iVs (a'J) efficiency of about 60% (both sides) and a maximum optical output of about 1007/IW could be realized. In this example, an infrared laser was used, but by increasing the amount of Al in the active layer and cladding layer, l,! , the present invention brings about exactly the same effect as a bilaser.
l, a substrate formed with two parallel ridges'-/+r
By forming each layer including two I(/I layers) and by making the shape of the groove between the ridges into a doptail shape whose depth changes discontinuously, a high-output "1" core body with fundamental transverse mode oscillation can be achieved. The laser can be realized, and its practical young fruit 1, there is something called human beings.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional semiconductor laser device, and Figure 2 (a
) to (C1 are cross-sectional views at each step of a method for manufacturing a semiconductor laser device in an embodiment of the present invention. 1---- n-type GaAs substrate, 2--n-type Ga 1y
A 1yAs cladding layer, 3...non-doped G
a, -xAlxAs active layer, 4... p-type Ga, -
yAlyAs cladding layer, 5...n-type Ga A
S layer, 6...The p-side ohmic electrode metal 111 is
7...Metal film for n-side ohmic electrode, 8...
...+111 lead diffusion area

Claims (1)

[Claims] Each layer including the active layer is formed on a substrate on which two parallel ridges are formed, and the groove between the ridges has a doptail shape in which the groove width changes discontinuously in the depth direction. A semiconductor laser device characterized by