JPS6373691A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To be able to manufacture a semiconductor laser by once crystal growth, to flatten the surface, to improve the bondability, and to efficiently escape the heat generated upon laser operation by forming a ridge also at a substrate except the region of the ridge for actually laser-operating to form a multilayer thin film having a double hetero structure including an active layer. CONSTITUTION:A photomask 10 is so formed as to form a stripe on an n-type GaAs substrate 2, and a ridge is formed by chemical etching. Then, an n-type GaAs buffer layer 3, an n-type AlyGa1-yAs clad layer 4, a nondoped AlxGa1-xAs active layer 5, a p-type AlyGa1-yAs clad layer 6, an n-type AlzGa1-zAs buried layer 7, and an n-type GaAs cap layer 8 are sequentially grown. Then, Zn is diffused at 11 to the layer 6 at the top of the ridge at the center, and n-type and p-type electrodes 1, 9 are formed. When a current is injected, the current is narrowed by the upper and lower parts by the ridge on the substrate 2 and the p-type region formed by diffusing Zn 11, thereby obtaining a semiconductor laser which oscillates in a single lateral mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor laser device, which has been rapidly used as a light source for various electronic devices and optical devices in recent years and is in increasing demand.

2. Description of the Related Art One of the important performances required of a semiconductor laser as a coherent light source for electronic equipment and optical equipment is single-transverse mode oscillation. To achieve this, 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. Such a semiconductor laser is usually called a stripe type laser. A buried stripe type semiconductor laser is a laser that can achieve the lowest threshold value and oscillates in a single transverse mode. Usually, two steps are required to fabricate an embedded semiconductor laser.
crystal growth was required.

Also, recently, a buried laser has been shown in which a convex ridge is provided on a substrate and is constructed on the ridge.

Problems to be Solved by the Invention However, in a buried semiconductor laser fabricated by providing a ridge on a substrate and performing one crystal growth, the grown surface becomes convex to reflect the shape of the substrate, and due to upside-down When assembled, there were drawbacks such as not only poor adhesion but also poor heat dissipation characteristics during laser operation, which adversely affected reliability.

In view of the above drawbacks, the present invention can be produced by one crystal growth,
Furthermore, the present invention provides a semiconductor laser device in which the grown surface can be flattened, bonding can be performed with good adhesion, and heat generated by laser operation can be efficiently dissipated.

Means for Solving the Problems In order to solve the above-mentioned problems, the semiconductor laser device of the present invention has a stripe-like convex portion formed on a substrate of one conductivity type, and a concave portion formed on both sides of the convex portion. On the substrate with convex parts,
Consists of a multilayer thin film with a double heterostructure including an active layer,
On both sides of the convex part, multilayer thin films are formed independently in the convex part and the concave part in the same order in the stacking direction up to at least the thin film layer immediately above the active layer, and directly above the multilayer thin film, a part of the thin film is formed with the substrate. It is constructed by using thin films that exhibit opposite conductivity types.

Function When crystal growth is performed by MOCVD or the like on a substrate provided with convex portions, growth begins independently on the portions above the convex portions and those not on the convex portions. When the layer thickness is further increased, the initially independent growth layers become connected. However, the growth surface becomes convex due to the influence of the substrate shape. If convex portions are provided on both sides of a convex portion provided on the substrate via concave portions, growth on the convex portions will occur in the same way, and the surface will be partially flattened without becoming convex.

In this manner, even if a convex portion is provided on the substrate and crystal growth is performed, a semiconductor laser having a flat surface can be manufactured.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of a semiconductor laser device in an embodiment of the present invention. In FIG. 1, 1 is the n-side electrode;
2 is an n-type GaAs substrate, 3 is an n-type GaAs substrate
Buff layer, 4 is n-type AI Ga As cladding layer, 6 is non-doped A73 Ga As active layer, 6
is p-type A I G a As cladding layer, 7 is n-type A
The IGaAs buried layer 8 is an n-type QaAs
A cap layer, 9 a p-side electrode, and 11 a Zn diffusion region.

Next, a specific tabulation method of the present invention will be explained. First, as shown in FIG. 2, (1
00) Form a photomask 1o to create 8 μm stripes at 8 μm intervals on the surface (Figure 6), chemical etching (for example, H2SO4:H2O2:H20=1:8:
8) 2.0 μ! Dig down to In and provide a ridge parallel to the (011) direction (Figure b).

Next, an n mGa As buffer layer 3 (thickness 05 μm) of n-type Al y Ga 1. A
s cladding layer 4 (y=o, 3 thickness 1.0 μm), non-doped Al x Ga 1x A s active layer 6 (x=
o, 1 thickness 0.1 μm), p-type A ly G a 1
-y As cladding layer 6 (y=0.3 thickness 1.1
μm), n-type A6Ga1-2As buried layer 7 (z=
α3 thickness 1.5 μm), n-type GaAs skip layer 8
(thickness O, S μm) is grown sequentially. At this time, n-type G
Since the aAs substrate 2 is provided with a ridge, growth occurs independently on the upper part of the ridge and on the other parts. In addition, growth occurs at the edge of the ridge while exposing the (111) plane, and in the vicinity, the growth rate is fast due to the odd elongation of 1 and 2λ.
The parts that are not in the mu layer 7 pu I juice 11, the bow 1 ■ rate 6 are connected and grow. Next, Zn diffusion 11 is performed up to the p-type cladding layer 6 above the center edge, and finally the n-side and p-side electrodes 1.9 are formed. When current is injected, the current is n-type Ga
It is narrowed at the top and bottom by the ridge portion on the As substrate 2 and the p-type region formed by the Zn diffusion 11. As a result, a semiconductor laser device that oscillated in a single transverse mode at a threshold current value of 30 mA was obtained. In addition, as in the present invention, the shape of the growth surface is considerably larger than that of growing on a single layer because the wafer is provided on the n-type GaAs substrate and is also provided outside the area where the actual laser operation is performed. It has been flattened, improving assembly yield and improving heat dissipation.

In this embodiment, GaAs and AlGaAs semiconductor lasers have been described, but the present invention can be similarly applied to semiconductor lasers made of compound semiconductors including InP and other multi-component mixed crystal systems. Alternatively, a p-type substrate may be used as the conductive substrate, and current stripes may be formed by ion implantation. Furthermore, for crystal growth, M
Although the OCVD method was used, the MBE method may also be used.

Effects of the Invention As described above, the feature of the present invention is that in a semiconductor laser in which a double heterostructure including an active layer is formed on a substrate provided with a ridge, a ridge is provided on the substrate even outside the area where the actual laser operation is performed. There it is. By adopting the structure of the present invention, the growth surface is more flattened than the conventional growth on a single glued edge, and as a result, when assembled upside down, bonding is achieved with good adhesion, and laser operation The accompanying heat can also be efficiently dissipated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a semiconductor laser device according to an embodiment of the present invention, and FIGS. 2a and 2b are diagrams showing the manufacturing process thereof. 1...n-side electrode, 2...n-type Ga
A s substrate, 3... n-type Ga As buffer layer, 4... n-type AI Ga As cladding layer, 6... non-doped AI Ga As
s active layer, 6...p-type AI Ga As
Cladding layer, 7...n-type A73 G a A
s buried layer, 8...n type Ga As cap layer, 9...p side electrode, 1o...
Photomask, 11...Zn diffusion region. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
N-side electrode? -n! ! traAs&jf1 3-=n Darn buffer 1 layer 4-n *AIeaAs)) La? FJ6=AJl
yaAs thermal layer 6-Pg! Al extraction As graft layer 1st Figure 7-, yt da Al[with] As embedded θ-719! (nAs solid layer P-P side electrode/1-7!41 (members jfA 2-= n'l Ga As certain grade lθ-photomask Fig. 2 C (1) (b)

Claims (1)

[Claims] By forming two recesses facing each other on a substrate of one conductivity type, a striped protrusion is formed between the two recesses, and a double heterostructure including an active layer is formed on the protrusion. A multilayer thin film is formed, and on both sides of the convex part, at least up to the thin film layer directly above the active layer, the multilayer thin film is formed in the same order as on the convex part in the stacking direction, independently of the top of the convex part, A semiconductor laser device characterized in that a thin film partially having a conductivity type opposite to the one conductivity type is formed directly above the multilayer thin film.