JPS63215091A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To relax the stress to be applied to both ends of a groove, to inhibit the generation of a dark line in an active layer and to obtain a highly reliable high-output operation by forming a GaAlAs layer having a mixed crystal ratio smaller than that of a first clad layer in the groove. CONSTITUTION:An Al0.30Ga0.70As stress relaxing layer 10 is formed in such a way as to fill a groove. The mixed crystal ratio of Al to As of the layer 10 is made smaller than that of a first clad layer 3. By making the thermal expansion coefficient of the AlGaAs of the layer 10 approach to the thermal expansion coefficient of the GaAs layer, the stress to be applied to both ends of the groove 9 becomes small. An active layer 4 and a second clad layer 5 are formed in order on the clad layer 3. Thereby, the generation of a dark line in the layer 4 is inhibited and a highly reliable high-output operation can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor laser device that can be used as a light source for optical information processing devices such as optical disk files and laser printers.

BACKGROUND OF THE INVENTION In recent years, demand for semiconductor laser devices with high visibility has increased in a wide range of fields such as optical disk files and laser printers. The present inventors have already developed BTRS (BurriadTwin-Ri) as a semiconductor laser.
We are proposing a semiconductor laser device with a dge 5ubs+trate) structure. FIG. 4 is a cross section of a visible light high output laser with a BTR8 structure and an oscillation wavelength of 750n11.

1 is a p-type GaAs5 substrate, 2 is an n-type GILA! 1 current blocking layer, 3 p-type Mukss Ga (1.45 MuS first cladding layer, 4 non-doped J0.20G" [
1,8OA" active layer, 6 is n-type MLO, ss Gaa
, 45mmS second cry)'' layer, e is an n-type GaAg contact layer, 7 is an n-side electrode, and 8 is a p-side electrode.
The figure shows the results of a life test of this visible light high-power semiconductor laser. The front and rear end faces of the cavity are coated with an end face protective film, reducing the reflectance of the end faces by 10% and 10% respectively.
It is set at 90chi. The life test was conducted in a nitrogen gas atmosphere at 70° C., and was driven at a constant optical output of 20 mW. The operating current increases significantly within several hundred hours.

Problems to be Solved by the Invention It is believed that the cause of the deterioration of the visible light high-power semiconductor laser within several hundred hours is the stress applied to both ends of the groove 9 in FIG. A11
．． J, Mpp1. Phys, 58.2448 (
(1985)). p-type G & M S substrate 1 and n-type Ga
Thermal expansion coefficient of As current blocking layer 2 and p-type Ga
o, ss lo, asAS Due to the difference in the coefficient of thermal expansion of the first cladding layer 3, the heat generation during laser oscillation causes
Stress is concentrated at both ends of 19. Due to this stress, dark lines were generated in the active layer 4, causing a significant problem in the reliability of the semiconductor laser.

In view of the above-mentioned drawbacks, the present invention provides a highly reliable visible light high power oscillation semiconductor laser device that suppresses the occurrence of dark lines by relaxing the stress applied to both ends of the groove.

Means for Solving the Problems In order to solve the above problems, the semiconductor laser device of the present invention has a G layer in the groove having a lower mixed crystal ratio than the first cladding layer.
It is constructed by forming an aAlliAs layer.

Effect: This configuration alleviates the stress applied to both ends of the groove, suppresses the occurrence of dark lines, and prevents deterioration of the semiconductor laser, resulting in high reliability for high-output visible light oscillation. Can be done.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a cross section of a semiconductor laser device in one embodiment of the present invention. 1 to 9 each have the same configuration as the conventional example. 1o is p-type Mlo, 3oGILo, 7o
A! It is a stress relaxation layer. The stress relaxation layer 1o is formed to fill the groove 9. The width W of the groove 9 and the film thickness of each layer are as follows.

W=6.0μml d++=1.4μnt d12
==0.02μm1 (113=0.30μm, d'
14:0.064m+d15=2.0μ”+d16
=2.5μm0 The stress relaxation layer 10 has a mixed crystal ratio of 1 As of the first cladding layer 3.
This is smaller than the mixed crystal ratio of . GaAs and MuEA
Letting the thermal expansion coefficients of S be αGaAg and αmuJAs, respectively, then mu1xGIL1. Thermal expansion coefficient αm of AsGaA
g is αA11(rlLAs = (1-x)txG
aAs +xahlhaαGams:6.86X10
('c) agAB = 5.20 x 10
('C) can be written (M, Ikeda etal
, J, People pp1. Phyg.

sa, 2448 (1985)). Therefore, MU4MUS
As the mixed crystal ratio X becomes smaller, α(lr
Approach aAs. Thermal expansion coefficient α of the stress relaxation layer 10/G
aλB '1GILA! Thermal expansion coefficient αGILA of i! !
By bringing the distance closer to , the stress applied to both ends of the groove 9 becomes smaller.

The operation of the semiconductor laser device having the above configuration will be explained below. FIG. 2 shows the relationship between optical output and operating current without an end face protection film. The threshold current value is 40mA,
The external differential quantum efficiency was 38%, and the maximum optical output was ssmW. An end face protection film was coated on the front and rear end faces of the cavity of this semiconductor laser device, and
Figure 3 shows the results of a high temperature accelerated life test using W.

Almost no increase in operating current was observed even after 5000 hours, and a highly reliable visible light high-power semiconductor laser was obtained.

Effects of the Invention As described above, by forming a GaAl1Ag layer with a lower mixed crystal ratio than the first cladding layer in the groove, the stress applied to both ends of the groove is relaxed and the generation of dark lines in the active layer is suppressed. As a result, highly reliable high-output operation can be obtained, and its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between optical output and operating current of a semiconductor laser device according to an embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view of a conventional semiconductor laser device, and FIG. 5 is a diagram of a high-temperature accelerated test of a conventional semiconductor laser device in one embodiment. 1...p-type GaAs substrate, 2...n-type GaAs current blocking layer, 3...p-type layer
o, 5sGAo, asss first cladding layer, 4...
...Non-dope person la, zoG&Q, aoAJ active layer,
6...N-type Ag o, ss Ga (1,45
MuS second cladding layer, 6...n-type GaAs contact layer, 7...n-side electrode, 8...p
Side electrode, 9...groove, 10...p type kl
a, 5oGLO,70As stress relaxation layer. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
p ri (4As Kokuma 7 ~ old mo 4: stock R --- fl (ll14 i0-piha172.go = a7-δ] t = Chikarakawa g42
For illustration 3 figure? , #, fr 75 (hour) lIJ4 Figure 5 Figure 1 Trial 1 (hour)

Claims (2)

[Claims] (1) A first semiconductor layer made of the compound semiconductor and having a conductivity type opposite to the one conductivity type is formed on a compound semiconductor substrate of one conductivity type; A groove with a depth reaching the substrate is formed, a second semiconductor layer made of a mixed crystal containing the compound semiconductor is formed on the first semiconductor layer so as to fill the groove, and the second semiconductor layer is made of a mixed crystal containing the compound semiconductor. A semiconductor characterized in that a first cladding layer made of a mixed crystal made of the same element as the mixed crystal of the second semiconductor layer is formed on the layer, and an active layer and a second cladding layer are further formed in sequence. laser equipment. (2) The semiconductor laser device according to claim 1, wherein the mixed crystal ratio of the compound semiconductor in the first cladding layer is smaller than the mixed crystal ratio of the compound semiconductor in the second semiconductor layer.