JPS6377184A - Manufacture of semiconductor laser array - Google Patents

Abstract

PURPOSE:To effectively manufacture a semiconductor laser array in such a manner that laser lights generated in an active layer are individually separated by absorbing light generated in the active layer directly on a current constriction layer by a thin first clad layer of the part to the current constriction layer. CONSTITUTION:A current constriction layer 13 which has a predetermined thickness and a flat surface is laminated directly on a stripe 12 on a substrate 11. Then, a plurality of grooves 14 extended perpendicular to this paper are formed on the whole layer 13. Such grooves 14 are formed at a depth larger than the thickness of the layer 13 directly above the mesa stripe 12 and smaller than the thickness of the layer 13 on the substrate 11 except the stripe 12, and so etched that the interval is set to a predetermined value and the widths of the layer 13 perpendicular to the extending direction of the groove are all of a predetermined value. Thereafter, a first clad layer 15 made of P-type Ga0.55Al0.45As and a second clad layer 17 made of nondoped Ga0.85Al0.15As are sequentially laminated by a liquid growing method on the layer 13 to form an oscillator layer 18, and a cap layer 19 made of n-type GaAs is thereafter grown on the layer 17.

Description

[Detailed description of the invention] B) Industrial application field The present invention relates to a method for manufacturing a semiconductor laser array.

-1 Conventional technology Figure 2+! FIG. 101 is a cross-sectional view of each step showing a method of manufacturing a semiconductor laser array based on a conventional vsxs type laser.

In this method, first, n-type Ga is deposited on a p-type GaA3 substrate (1).
Current confinement 1 made of Al! # (forming 21 (second
Figure (a)). Next, the substrate (
1), grooves (3) extending perpendicular to the plane of the paper are formed at regular intervals equal to the number of semiconductor lasers to be arranged on the substrate (1). J112 figure (bl)
.

After that, the current confinement l11123 surface has p-type C)&1-X
Ml consisting of Al x A a (0<x<1)? 7
Do, h (4), / y Dog () al-4AA'YA
Activity 111T51.l (0≦Y×0, Y<X).
A second cladding layer (6) made of n-type ()lLl-XAlxAm and a cap layer (7) made of n-type G&AII.
) are sequentially stacked (!g2 (C)).

The semiconductor radar array formed in this way has a theoretical i: when a forward bias is applied between the substrate (1) and the cap@(7), it is generated from the active layer (5) other than directly above the groove (3). Since the light is absorbed by the current confinement layer (41C) with a small bandgap energy, the active II layer directly above the groove (3)
! Only the light generated within the groove 51 is output as a laser beam separated by each groove.

However, in the case of a semiconductor laser array, it is necessary to make the distance between the lasers as small as possible (approximately 1 μm), and for this reason, the width of the current confinement layer (2) between the grooves (3) is determined by the second factor (t).
As is clear from ll, the width is much narrower than the width of the overhead current confinement layer (2) in which the groove (3) is not formed.

Therefore! When the J1 cladding layer (4) is formed using the liquid phase growth method, only the current confinement layer (2) between the grooves (3) is largely melted back and its thickness becomes thinner, as shown in FIG. When the current confinement 1 (2) between fi (31) becomes thinner, the surface of S11 becomes flat (4)'I
If T is formed, the first cloud (4) in this part will become thicker than expected, and the light absorption effect in this part will be enhanced, causing the laser light output from the active layer (5) directly above each groove to decrease. Separation becomes impossible.

In view of this point, Sharp Technical Report '1J133 No. 1985
From p15 to p13 in 2013, it was proposed to use GILAjAa which is melted back as a current confinement layer.

Problem to be solved by the invention No. 1: When GaA/Aa'li is used as a current confinement layer, an It oxide film is generated on the surface of the current confinement layer during trench formation.
There is a problem in that it becomes difficult to grow the first crud.

B) 1. Means to solve the problem The present invention has been made in view of the above problems.

Its structural features include the first step of forming mena stripes on the surface of the semiconductor substrate;
step, a portion ζ larger than the layer thickness of the current confinement layer on the menastrive and other than on the mesa stripe; having a depth smaller than the layer thickness of the formed current confinement layer and parallel to the mesa stripe; A third step of forming a plurality of grooves extending at equal intervals on the surface of the current confinement layer, an active layer and a pair of cladding layers sandwiching the active layer on the surface of the current confinement layer in which the grooves are formed; The method consists of a fourth step of laminating oscillation layers.

(e) Effect: With this method, the width of the active current confinement layer is uniform, so the meltback of the current confinement layer occurs uniformly.

(f) Example FIG. 1 (&l~((11 shows an embodiment of the present invention.

First, as shown in FIG.
Etch the surface of the substrate except for the surface.

Direction ζ perpendicular to the plane of the paper: Mesast 911 portion α2 to be rolled is formed.

Next, as shown in the first etb port, on the surface of the substrate (11) (varnish drive portion (13), a current confinement layer 3 having a thickness of approximately 1 μm and a flat surface is laminated. is made of n-type C) ILA@, and a well-known epitaxial growth method such as a liquid phase growth method or a vapor phase growth method can be used for its growth.

Thereafter, as shown in FIG. 10)C, a plurality of grooves α4 are formed on the surface of the current confinement layer in a direction perpendicular to the plane of the paper. The depth of such groove I is equal to the mesa stripe portion of the substrate +
The width of the current confinement layer in the direction orthogonal to the extending direction of the groove is 242 m in all cases.
It is formed by a well-known etching technique so that

After that, as shown in FIG. 1, on the electrical constriction layer u3, a first semiconductor layer consisting of p-type G&0.55AJ0.45As, non-doped GaO, 85AJO,
Active n(Lti and n-type Oa Q, 5
2nd cladding made of 5Al 145Aa l1t17)
(1G liquid phase growth method); Forming Q& and then inn on the second club, Do Itiαη
Type G! A cap layer α9 made of LAll is grown.

The first cladding layer (1) has a thickness of about 0.1 μm on the current confinement layer 3 and is formed so that its surface is flat. Layer (1
7) and Cap IIIα9 each have a layer thickness of 0.05
1: Formed so that the diameter is about 1 μm, 1 μm, and 2 μm, and the surface is flat.

In a semiconductor laser array formed in this way,
Since the width of the current confinement mt13 is uniform at 1 μm, the first
The meltback of the current confinement layer α3 that occurs during the formation of the cladding bus occurs uniformly. As a result, the first Clad ens
Even when formed with a flat surface, the first cladding layer α9 on the current confinement layer a3 can be controlled to have a uniform thickness of 1 μm.

Therefore, when a bias in the C binomial direction is applied between the substrate αυ and the cap layer α1, light is emitted in the active layer immediately above the groove a4 on the stripe portion 112 due to the current confinement m (13). However, at this time, the light generated in the active layer ae above the current confinement layer (131i1) is absorbed by the current confinement II (13) because the first cladding layer (15) in that part is as thin as 0.1 μm. Therefore, the laser light generated within the active layer αe above the groove chamber on the stripe portion az can be extracted in the form of two separate parts.

(G) Effects of the Invention According to the present invention, even when the current confinement layer is formed of a material that is easily melted back, each laser beam can be reliably separated.

[Brief explanation of the drawing]

FIG. 1(al~(al is a cross-sectional view by process showing an embodiment of the present invention, FIG. 2jal~(C1 is a cross-sectional view by process showing a conventional example. ...Mesa stripe part. (13-...Current confinement 11.C41...Groove, fi9...
...First cladding layer. αG...Active layer, (17)...Second closed layer,
α... oscillation layer.

Claims (1)

[Claims] (1) A first step of forming a mesa stripe on the surface of a semiconductor substrate, a second step of forming a substantially high-resistance current confinement layer with a flat surface on the surface of the substrate, and current confinement on the mesa stripe. a plurality of grooves having a depth greater than the layer thickness of the current confinement layer and smaller than the layer thickness of the current confinement layer formed in a portion other than the mesa stripe, and extending parallel to the mesa stripe at equal intervals; A third step of forming on the surface of the current confinement layer, and a fourth step of laminating an oscillation layer consisting of an active layer and a pair of cladding layers sandwiching the active layer on the surface of the current confinement layer where the grooves are formed. A method of manufacturing a semiconductor laser array, characterized in that: