JPH01214085A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain a high output and long life semiconductor laser device in which a residual stress can be relieved by a method wherein a stripe type uppermost layer is provided directly above the position of a trench in a blocking layer and a layer beneath the blocking layer has a stripe type mesa directly below the uppermost layer. CONSTITUTION:On a one conductivity type compound semiconductor substrate 1, a layer 2 which has a conductivity type opposite to that of the substrate 1 and has a V-trench whose bottom reaches the substrate 1 is provided and an active layer 4 sandwiched between semiconductor layers 5 and 3 with larger forbidden band widths is provided on it. The semiconductor layer 3 closer to the substrate 1 has a conductivity type same as that of the substrate 1 and the other semiconductor layer 5 has a conductivity type opposite to that of the substrate 1. Further, an uppermost layer 6 with a conductivity type opposite of that of the substrate 1 is provided and its lower layer 5 form a protrusion above the trench. For instance, the uppermost n-type GaAs layer 6 and the n-type Ga0.55Al0.45As layer 5 under the layer 6 form a mesa at the position corresponding to the trench provided in the blocking layer 2 and the mesa relieves a stress in the active layer 4.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an optical disk memory and a laser printer.

The present invention relates to a semiconductor laser device used as a high-output light source for direct optical communication and the like.

BACKGROUND OF THE INVENTION In recent years, the demand for semiconductor lasers has been increasing, mainly as light sources for optical disks, and in particular, semiconductor lasers with higher output power are required for faster writing and erasing speeds on disks. . On the other hand, as semiconductor lasers increase in output, -C1 tends to deteriorate more severely when operated for long periods of time, and the development of high-output, long-life semiconductor lasers has become a major challenge. Several causes of deterioration have already been clarified, one of which is residual stress within the active layer, which is the light emitting part. FIG. 3 is a cross-sectional view of a semiconductor laser having a conventional structure, and FIG. 4 shows the results of calculating the stress distribution within the active layer 4 for this laser. A large concentration of stress can be seen at the shoulder of the groove, which coincides with the location where many non-light-emitting parts of a deteriorated element are seen, indicating that residual stress is a major cause of element deterioration.

Problems to be Solved by the Invention Residual stress leads to the proliferation of crystal dislocations during long-term operation.
This causes a decrease in luminous efficiency and an increase in operating current. Although residual stress depends on the laser structure and material composition, the present invention provides a semiconductor laser device with a new structure that can reduce stress.

Means for Solving the Problems The semiconductor laser device of the present invention has a striped top layer directly above the groove position of the block layer, and a layer below the striped top layer has a striped convex portion directly below the top layer. It is configured with

action Figure 2 shows the results of calculating the stress in this case.

Due to the effect of the mesa provided on the top of the groove, the stress in the active layer ii:
It is reduced to 1×1oPa (Pascal) or less.

Embodiment FIG. 1 shows a sectional view of a semiconductor laser device according to an embodiment of the present invention. The difference from the conventional example shown in FIG. 3 is that the top layer of n-GaAs 6 and the n-Gaα55μEα45μS5 below form a mesa at the same position as the groove provided in the block layer 2. It is a point. It is clear from the calculation results shown in FIG. 2 that this mesa functions to relieve stress within the active layer 4. The structure of each layer is as shown in Figure 1, and the thickness of each layer is -n-GaAs layer 2 is 1
7zm, p-GaM JA8 layer 3 is 0.2 μm%
GILAJAI layer 4 is 0.05 μm −n −GaA
AtAs N5 is I Q l1m, n in the part without mesa
-The GaAs layer 6 is 10 μm, and the mesa height is 3.0 μm. The groove has a width of 7 μm and a depth of 1.5 μm. The element is G which formed a mesa! Fabricated on LAS substrate 1 by twice liquid phase epitaxial method, n -GaAji! A! ! After forming the mesa of layer 6 and depositing the wires 7 and 8, the shrimp is mounted on a heat sink with the growth side facing down.

FIG. 6 shows the results of continuous energization operation of the semiconductor laser according to the present invention and the conventional semiconductor laser under conditions of 70 tl: and 5αl. It is clear that the lifespan is longer than that of conventional lasers, and deterioration is suppressed by stress relaxation.

Effects of the Invention Since the semiconductor laser of the present invention has high output and high reliability, it has practical effects for use in optical discs and communications.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the semiconductor laser of the present invention, FIG. 2 is a diagram showing the stress calculation results in the active layer, FIG. 3 is a cross-sectional view of the conventional semiconductor laser, and FIG. 4 is the stress calculation in the active layer. FIG. 5 is a diagram showing the results of a continuous current test. 1...7-Ga 3 board, 2I...n
-GaAs layer, 3...p -GILAJAg layer, 4...G&M1111 layer, 6...n
-GaAlAs layer, 6 ·-·---n -GaJ
k1 layer. Name of agent: Patent attorney Toshio Nakao and one other person No. 2
Figure
---6a-o, B5, l)o, tsAs layer S --
-n-(r(tO,5sA)o, as A 5 layers 6-
--yt-(to-AS layer Fig. 3 7-Aa-Cre Ni/Att 9.
Swelling 8 --- Cr Pt A, L'LX! The fourth
Fig.

Claims (1)

[Claims] On a compound semiconductor substrate of one conductivity type, there is a layer of the opposite conductivity type to the substrate, which has a V-shaped groove deep enough to reach the substrate, and on top of that, a semiconductor layer with a larger forbidden band width is formed from above and below. There is a thin active layer sandwiched between the semiconductor layers, and the conductivity type of the semiconductor layers on both sides of the active layer is the same conductivity type as that of the substrate on the side closer to the substrate, and the opposite conductivity type on the side closer to the substrate. A semiconductor laser device characterized in that there is an uppermost layer of a conductivity type opposite to that of the uppermost layer, and the uppermost layer and the lower layer form a convex portion on the groove.