JPS6144485A - Semiconductor laser device and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain the titled device which oscillates on single lateral modes at low threshold value by a method wherein a stripe active layer with a small width is buried with good reproducibility at a time of crystal growth by providing the surface of a conductive substrate with a stripe projection having a required shape. CONSTITUTION:A photo resisto 10 of (d) width is provided on the (100) plane of an N type GaAs substrate 10 and then etching into the stripe projection 10a in the <011> direction: the top surface makes an internal obtuse angle, and the internal angle made by the continuous side surface between the top surface should be less than 90 deg.C. Next, an N-Ga1-xAlxAs 11, a Ga1-yAlyAs active layer 12, a P-Ga1-xAlxAs 13, and an N-GaAs 14 are laminated by the vapor phase epitaxial method. A photo resist 17 is applied by spinning. The resist 17 and the projection located on the plane 19 are removed by etching from the surface. A P-GaAs layer 15 is formed on the projection 13 of the clad layer 13 by Zn diffusion with a width (d). When current is injected by attaching ohmic electrodes on both surfaces 20 and 21, the current is effectively subjected stricture above and below because the width (w) of the P-layer 15 is smaller than the tip width WR of the projection 10a, leading to single lateral mode oscillation at low threshold current value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor laser device and a method for manufacturing the same, whose use as a light source for electronic devices and optical devices in various countries has rapidly expanded in recent years, and whose demand has been increasing.

Conventional Structure and Its Problems Kiko 11 One of the important performances required of the semiconductor laser 1ζ as a coherent light source for optical equipment is oscillation in a single spot, that is, single-spot mode oscillation. To achieve this, it is necessary to suppress the spread of 1ζ and confine the light so that the current flowing through the 1ζ laser element is concentrated near the active region where the laser light propagates. Semiconductor lasers like the stripe type are usually called stripe-type semiconductor lasers.

A relatively simple striping method uses only current constriction. Although these lasers achieve single-transverse mode oscillation, the threshold value 1j is high.

A buried stripe type semiconductor V-laser (usually called a BH laser) is a stripe structure that provides the lowest threshold voltage. However, creating this laser typically requires two crystal growth steps, compared to one for other lasers.
It requires several times, and it is technically difficult to manufacture.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a semiconductor laser device capable of single-mode oscillation and low-threshold operation, in which a buried stripe structure necessary for 1ζ can be fabricated by one crystal growth. The purpose is to

SUMMARY OF THE INVENTION In order to achieve this object, the semiconductor laser device of the present invention has a conductive substrate having an internal angle formed by an obtuse flat end surface and an adjacent side surface, and at least a base end that continues to the adjacent side surface. A striped convex portion formed such that the internal angle between one side surface and the flattened surface of the tip is 90@ or less, a conductive substrate jlζ including the convex portion, and an active I! A multi-mvsys having a double heterostructure including a 1″ calendar, and independently formed in the same order in the stacking direction 1ζ at least up to the thin film layer directly above the active layer on both side surfaces along the adjacent side surfaces of the convex portion. ythm of the multilayer thin film corresponding to the convex portion
This structure narrows the current in the active layer with the striped protrusions, resulting in single-transverse mode oscillation and a low threshold current value. An operational semiconductor laser device can be realized. In addition, as a method for manufacturing the semiconductor laser device described in h above, if a metal organic vapor phase epitaxial growth method is used, a buried stripe structure can be easily formed by one crystal growth.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. - As an example, an n-type GaAs substrate is used as the conductive substrate. n-type C
aAs substrate Q (<100> plane kl of I, photoresist for mesa etch with mesa mask width d as shown in FIG.
Using as a mask, parallel 1ζ unevenness is provided in the <01D direction by chemical etching. As a result, a striped protrusion with a width of 6 μm and a height of 1.6 μm is formed as shown in FIG.
5 (loa) is formed such that the internal angle formed between the flat tip surface and the adjacent side surface is an obtuse angle, and the internal angle formed between at least one side surface of the proximal end that follows the above-mentioned calf-contacting side surface and the flat surface is 90@ or less be done.

Next, metal organic vapor phase epitaxial growth method (usually MOC
As shown in FIG. 4, n-type Ga I-
1AIX As cladding layer @"l"'s 7
Ga1-yAZyAs (0≦y<x) Active Hta is 0.08μfn°, p-type Ga1-xAtzAs
After forming the cladding 71 Qi 'k 1.2 μm, a crystal of an n-type GaAs cap ItA04 is grown to 2 μm. - As an example, the crystal growth conditions are a growth rate of 2 μm
/hour, growth temperature 770'' C1 total gas flow, molar ratio of Y group elements to group II elements is 4o.

As can be seen from Figure 4 ■ζ, p-type Ga I-, cA
I
f: and other parts are epitaxially grown independently of each other, and crystal growth with effects such as diffusion of the growth material in a direction parallel to the growth substrate surface is not observed.

After the crystal growth, the surface was cleaned, and then a photoresist film was applied to the n-type GaAs cap l1164.
When the photoresist S is rotated at 00 rpm, as shown in FIG. 4, it becomes thinner at the convex portion (14a) of the n-type GaAs cap layer U, and becomes thicker at other portions.

By optimizing the exposure conditions, the convex portion (14a) and the photoresist film are removed, and the n-type GaAs cap layer is flattened so as to form the surface shown in FIG. Further, Zn is diffused with a stripe width W, and the convex portion (10a) and the convex portion (Nla) of the cladding 1 (2) corresponding to h are formed in the striped pl! 1iGaA
Form s region 4. As a result, the semiconductor laser structure shown in Figure 1 is formed, and the Ohmink electrode is attached to the plane gJ through the aX pole! When fi implantation is performed, the current is narrowed below t by the convex portion (lOa) of the n-type GaAs substrate 0Q and the p-type GaAs region 4 formed by diffusion.

Moreover, as shown in FIG.
) The stripe width W of the pWGaAs region aa is smaller than the width WR of the tip, and the current narrowing effect is large.
This is thought to be due to the fact that crystal growth was performed with the tip of the convex portion shaped like a forward mesa lζ, and that facets appear on the crystal growth surface at the side surfaces of the convex portion. As a result, a semiconductor laser device that oscillates in a single transverse mode with a fortune-telling current value of 26 mA was developed.

Furthermore, the semiconductor laser structure of the present invention is a buried type, and while other buried lasers require two crystal growths, the buried laser of the present invention can be fabricated by IIgl crystal growth. It is possible.

In addition, in Figure 1, the n-type "G" and the As substrate (g) and the n-type "G"
Similar results were obtained with the structure 1ζ in which an n-type GaAs buffer shoulder was inserted between the z 1-xA l x As clad shoes (b).

FIG. 6 shows another embodiment, in which the shape of the convex portion (80a) of the n-type GaAs substrate (toward) is such that the bottom of the proximal side surface is formed into a slope (2) with an outward wave. The same results were obtained even when crystal growth was performed on C.

In this embodiment, GaAs-based and GaAlAs-based semiconductor lasers have been described, but the present invention is also applicable to semiconductor lasers made of compound semiconductors including lnP-based and other multi-component mixed crystal systems. .

Furthermore, regarding the conductive substrate, even if a p-type substrate is used,
Other substance supply rate-limiting crystal growth methods, such as molecular beam epitaxial growth (MBE), may be used for crystal growth.

Effects of the Invention According to the present invention, a narrow stripe active layer can be easily formed with good reproducibility by one crystal growth, and a buried laser that oscillates in a single transverse mode with a low threshold current value can be realized.
Its practical effects are remarkable.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of a semiconductor laser device of the present invention, FIGS. 2 to 4 are diagrams showing the manufacturing process, and FIG. 6 is a broken shape of a substrate used in another embodiment. FIG. 00- n-type GaAs substrate, Qto-n a Ga1-x
AtxAs cladding layer, (La-Ga 1-yAj, A
s active layer, up type Ga 1-XA t xA s craft layer, 04- n type GaAs region, 0...
aAs area, Korea...photoresist film for mesa etch,
Sub: Photoresist film, (wR): Width of the tip of the convex portion, (B): Current narrowing stripe width, (d): Mesa mask width.

Claims (1)

[Scope of Claims] 1. On the surface of the conductive substrate, an internal angle formed between the flat tip surface and its adjacent side surface is an obtuse angle, and an angle formed between at least one side surface of the proximal end continuing from the adjacent side surface and the flat tip surface. A striped convex portion formed with an internal angle of 90° or less, and a double heterostructure including an active layer on a conductive substrate including the convex portion, and along an adjacent side surface of the convex portion. Both sides also have multilayer thin films formed independently in the same order in the stacking direction up to at least the thin film layer immediately above the active layer, and the uppermost layer of the multilayer thin film corresponding to the convex portion is connected to the substrate. A semiconductor laser device configured with a thin film that exhibits the same conductivity. 2. A striped convex portion is formed on the surface of the conductive substrate, and the internal angle formed between the flat tip surface of the convex portion and the adjacent side surface is an obtuse angle, and at least one side surface of the proximal end continuing from the adjacent side surface and the flat tip surface are formed. Formed so that the internal angle formed by the bearing surface is 90° or less,
A multilayer thin film having a double heterostructure including an active layer is grown on the conductive substrate including the convex portion by metal organic vapor phase epitaxial growth, and the top layer of the multilayer thin film corresponding to the convex portion is grown by Zn diffusion. A method for manufacturing a semiconductor laser device in which a thin film layer exhibits the same conductivity as the conductive substrate.