JPH0356066Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields The present invention relates to semiconductor lasers.

(b) Conventional technology Figure 3 shows a conventional semiconductor laser, and 1 is a P-type laser.
100μm thick GaAs substrate, 2 is n-type
The current confinement layer is made of GaAs and has a thickness of 1.2 μm.
A V-shaped groove reaching the substrate 1 from the surface of the constriction layer is formed. 3 to 6 are first layers made of p-type Ga _0.5 Al _0.5 As that are sequentially laminated on the current confinement layer 2;
A clad layer, an active layer made of undoped Ga _0.8 Al _0.2 As, a second clad layer made of Ga _0.5 Al _0.5 As, and a cap layer made of n-type GaAs, each of which has a thickness of 0.2 μm, 0.1 μm, 1.5 μm, and 2 μm, respectively. It has a layer thickness of Reference numerals 7 and 8 are first and second electrodes formed on the back surface of the substrate 1 and the surface of the cap layer 6, respectively.

(c) Problems that the invention attempts to solve However, with regard to such semiconductor lasers,
Electronics), Vol.QE−17, No.5, ppr763
(1981), differences in the composition of each layer generate internal stress, which causes deterioration.
Specifically, the laminated layers such as the active layer 4, the first electrode 7, and the second electrode 8 each contain 5.0×10 ⁷ Dyne/cm ^{2 .}
compressive stress of 1.5×10 ⁷ Dyne/cm ² and
A tensile stress of 3.0×10 ⁷ Dyne/cm ² is generated, and the stress as shown by the arrow in the figure is generated as a whole, so that the active layer 4 is curved and distorted.

(d) Means to solve the problem This invention was made in view of the problem.
Its structural feature is that a substrate having a double heterostructure on one main surface has a relaxation layer formed by wrapping on the other main surface side.

(e) Effect The stress generated in the relaxation layer becomes tensile stress, and its magnitude is determined by the degree of wrapping.

(F) Embodiment FIG. 1 shows an embodiment of the present invention, which differs from the conventional device shown in FIG. 3 in that a control layer 9 is formed on the back surface of the substrate 1 by wrapping. The first
In the figure, the same parts as in FIG. 3 are denoted by the same numbers, and the explanation will be omitted.

Specifically, the relaxation layer 9 is formed by applying a load of 5.5×10 ^-2 Kg/ to the back surface of the semiconductor laser substrate 1 while dropping an aqueous solution in which garnets with a particle size of 10 μm are dissolved as a wrapping material onto a rotating alumina plate. It is formed by pressing it against the alumina plate with a force of cm ² . Further, the relaxation layer 9 has a layer thickness of about 8 μm, and its internal stress is a tensile stress of about 3.5×10 ⁷ Dyne/cm ² .

Therefore, in this embodiment, compressive stresses of 5.0×10 ⁷ Dyne/cm ² and 1.5×10 ⁷ Dyne/cm ² are generated in the laminated layers such as the active layer 4 and the first electrode 7, respectively, and the second
Since tensile stresses of 3.0×10 ⁷ Dyne/cm ² and 3.5×10 ⁷ Dyne/cm ² are generated in the electrode 8 and relaxation layer 9, respectively,
As a whole, the internal stress is completely canceled out and becomes zero. Therefore, the active layer 4 etc. are not curved.

FIG. 2 shows the results of the life test. In the figure, the mark indicates the result of the device of this embodiment, and the mark Δ indicates the result of the conventional device. In this life test, changes in drive current were investigated during continuous oscillation with an output of 3 mW in a high temperature atmosphere of 70°C.

As is clear from Fig. 2, in this example device,
The drive current hardly changed even after 4000 hours of continuous oscillation, but in the conventional device, a sharp rise in the drive current was observed after several hundred hours of continuous oscillation.

In this example, garnet was used as the wrapping material, but alumina may also be used, and the particle size of the wrapping material is 3.5 times the tensile stress of the relaxation layer 9.
10 ⁷ Dyne/cm ² is preferably about 10 μm. For example, when the grain size is 1 μm, 4 μm, and 17 μm, the stress in the relaxation layer 9 is 2.0×10 ⁷ Dyne/cm ² and 3.0×10 ⁷ , respectively.
Dyne/cm ² , 4.0×10 ⁷ Dyne/cm ² , and the internal stress cannot be offset.

(g) Effects of the invention In the semiconductor laser of the invention, the presence of the relaxation layer cancels out internal stress, thereby preventing strain from occurring in the active layer, resulting in a longer life.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing life test results, and FIG. 3 is a sectional view showing a conventional example. 1...Substrate, 9...Relaxation layer.

Claims (1)

[Scope of utility model registration request] 1. A semiconductor laser comprising a substrate having a double heterostructure on one main surface and a relaxing layer formed by wrapping on the other main surface side.