JPS6262576A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To control lateral mode of low threshold value and high efficiency by providing a photoabsorbing layer necessary for photoconduction near an active layer, and forming a current narrowing layer at father position to eliminate a thyristor effect. CONSTITUTION:A P-type GaAs current narrowing layer 2, and an N-type GaAs photoabsorbing layer 3 are sequentially grown by an MOCVD method on an N-type GaAs substrate 1, and a groove 8 is then formed by etching. Thereafter, a flat N-type Ga0.55Al0.45As clad layer 4, an undoped GaAs0.86Al0.14As active layer 5, an N-type Ga0.55Al0.45As clad layer 6, a P-type GaAs cap layer 7-1 are sequentially grown by a liquid-phase growing method, and then an N-type electrode 11 and a P-type electrode 12 are formed. The roles of photoabsorbing and current narrowing are separately shared for the photoabsorbing layer and the current narrowing layer, the photoabsorbing layer is provided near the active layer and the narrowing layer is formed at further side, thereby eliminating a thyristor effect. Thus, a semiconductor laser which has high yield, low threshold value and high efficiency can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a transverse mode controlled semiconductor laser that oscillates with low threshold and high efficiency.

[Background of the invention]

CS P (Cbanneled 5ubstrat
e Planar type lasers have current confinement due to selective Zn diffusion, but there is a problem in that the current spreads by the time it reaches the active layer. Also, VSIS (V-g
rooved 5ubstrate Inner 5t
type laser (Yamamoto et al., Applied Physics Letters Vol. 40, p. 372, 1982 (S
, Yama-moto et al., , Ap.
pl, Phys, Lett, Vol.

140, 372 (1982)) had the limitation that current confinement could not be achieved due to the thyristor effect unless the current confinement layer was doped with an n-type cavity.

[Purpose of the invention]

An object of the present invention is to provide a transverse mode controlled semiconductor laser with a low threshold and high efficiency.

[Summary of the invention]

In conventional internal current confinement type lasers, light absorption and current confinement are performed in one layer, so there is a problem that current confinement cannot be achieved due to the thyristor effect caused by light absorption. Therefore, in the present invention, if a light absorption layer that requires optical waveguide is provided near the active layer and a current confinement layer is provided far away, almost no light will reach the current confinement layer, resulting in a thyristor effect. I made it disappear.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1. FIG. 1 is a schematic cross-sectional view of the semiconductor laser of the present invention. First, the manufacturing method of this semiconductor laser will be described. A p-GaAs current confinement layer (0.3 am) 2. on the n-GaAs substrate 1; n-GaAs light absorption layer (0.3μ
m) 3 by metal organic pyrolysis vapor deposition method (MOCVD method)
It grows sequentially. Next, a groove 8 having a depth of 0.8 μm and a width of 3 μm is formed using a phosphoric acid-based etching solution. After that, n Ga o, s s A go, 45As cladding layer 4% undoped Ga o, s 6 A e , 14
As active layer 5, p Ga o, s sA g 0.
45A3 cladding layer 6, p-GaAs cap layer 7-1
is grown using the liquid phase epitaxy (LPE method). At this time, the n-cladding layer 4 is made flat. Finally, the n-electrode 11 and the p-electrode 12 are provided using a vapor deposition method, thereby completing the manufacture of the semiconductor laser of this example.

When we measured the optical output-current characteristics of the laser of this example, the red current was 50 mA s, and the efficiency was 0.30 mW/
It was mA. The wavelength was 0.78 μm, and the light output was oscillated in the fundamental transverse mode up to 30 mW.Example 2 FIG. 2 is a schematic cross-sectional view of the device of the present invention. The difference from Example 1 is that an n-GaAs cap layer 7-2 is used instead of the p-GaAs cap layer 7-1, and the n-GaAs
p-Ga o55A g from the surface of cap N17-2
o, 45As cladding layer 6 selectively
This is because n is diffused. In this embodiment, since both the electron current and the hole current are constricted, the threshold value is lower and the efficiency is higher than in the first embodiment. In fact, as a result of measuring the device characteristics, the threshold current was 25mA.

The efficiency was 0.45 mW/mA. The wavelength was 0.78 μm, and the light output oscillated in the fundamental transverse mode up to 40 mW.

The present invention can be similarly applied to general semiconductor lasers using semiconductor laser materials other than GaAJAs-based, such as InGaAsP-based and InGaP-based compound semiconductors.

〔Effect of the invention〕

According to the present invention, the roles of light absorption and current confinement, which were conventionally performed in one layer, are divided into the light absorption layer and the current confinement layer. Since it is provided on the far side, the thyristor effect will not occur. Therefore, according to the present invention, a semiconductor laser with a low threshold value and high efficiency can be obtained with good yield.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an element according to a first embodiment of the invention, and FIG. 2 is a sectional view of an element according to a second embodiment of the invention. 1-n GaA3 substrate, 2-p-GaAs current confinement layer, 3-n-GaAs light absorption layer 1.4-Gao
, 55Ajo4. As cladding layer, 5... undoped GaO, 86" 0.14As active layer, 6"'p
-Gao55A#, 5As cladding layer, 7-1-p-
GaAs cap layer, 7-2-... n-GaAs cap layer, 8... groove, 9- n electrode, 10... p electrode, 11... Zn diffusion region.

Claims (1)

[Claims] 1. After sequentially providing at least a second semiconductor layer of the second conductivity type and a third semiconductor layer of the first conductivity type on the first semiconductor layer of the first conductivity type, A groove stripe is formed by etching the third semiconductor layer until it penetrates through the third semiconductor layer, and then at least a fourth semiconductor of the first conductivity type is formed on the first, second, and third semiconductor layers having the groove stripe. a fifth semiconductor layer having a larger refractive index and a smaller forbidden band width than the fourth semiconductor layer and a larger forbidden band width than the third semiconductor layer; a fifth semiconductor layer having a smaller refractive index than the fifth semiconductor layer and a forbidden band width; A semiconductor laser device comprising a sixth semiconductor layer of a second conductivity type having a large band width. 2. In the semiconductor laser according to claim 1, after providing a seventh semiconductor layer of a first conductivity type on the sixth semiconductor layer, impurities of a second conductivity type are added to the seventh semiconductor layer above the groove stripes. A semiconductor laser device characterized in that the semiconductor laser is introduced from the surface of the semiconductor layer until it reaches the sixth semiconductor layer. 3. In the semiconductor laser according to claim 1 or 2, the first, second, and third semiconductor layers are made of Ga.
A semiconductor laser device characterized by being made of As. 4. A semiconductor laser device according to claim 3, wherein the first semiconductor layer has an n-type conductivity.