JPS6072289A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To prevent a crystal from being damaged and enable to obtain the effect of sufficient current stricture by a method wherein a stripe-form diffused region, a single crystal region thereon, and polycrystalline layers on both sides thereof are formed on a double hetero structure. CONSTITUTION:An N-AlxGa1-xAs layer 11, an AlyGa1-yAs layer 12, and a P-AlxGa1-xAs layer 13 are formed on an N<+> GaAs single crystal substrate 10. N-GaAs single crystal layers 26 having the stripe-form P type diffused region 27 are selectively formed thereon, and a P<+> GaAs single crystal layer on the region 27, and P<+> GaAs polycrystalline layers 25 on the layers 26. In the tilted device of this structure, the current is put in stricture by the P<+> GaAs single crystal layers and the region 27, and accordingly a low threshold value can be realized. Besides, the P<+> GaAs single crytal region is electrically connected to the layer 13 via region 27; whereas a P-N junction is formed by the layer 13 and the regions 26, and current stricture is carried out in the region 27.

Description

[Detailed description of the invention] Industrial applications The present invention is a digital audio disc.

The rV3 is used as a coherent light source for video discs and other semiconductor devices, and is used as a light source for various electronic devices.

Conventional configurations and their problems One of the requirements for semiconductor lasers as light sources for electronic devices is oscillation in a single spot, that is, single-spot oscillation.
There is horizontal mode excavation. To achieve this, it is necessary to confine light and current near the active region. Regarding light confinement, the active layer is sandwiched between double heterostructures, and the entire refractive index is set in the straight direction to confine the light.
Alternatively, there is a method of causing a current to flow through a part of the active layer so that the optical amplification factor is distributed in the active layer and confined.

Concerning current confinement, that is, carrier confinement, the double heterostructure sandwiches the entire active layer and is confined by the structure of the energy band of electrons in the semiconductor, and in the direction perpendicular to the double heterostructure, it is confined only near the active region. A common method is to provide a striped current confinement region to allow current to flow.

FIGS. 1A to 1C show typical conventional stripe structure lasers. In these figures, 10 is +n-GaAs substrate, 11 is n-A 1xCrh1-x
As layer, 12 is AlxGa1. As (0<y<x)
layer, 13 P-AlxGa1, As layer, 14 P
-GaASIii, 15 is an active region, 16 is a stripe portion, 17 is an n-GaAs layer, 21 is a high resistance region fully irradiated with protons, 22 is a Zn diffusion region, 23 is a SiO2
It is a membrane.

(a) shows a laser in which a stripe portion 16 is formed by irradiating all of the protons from above the P-GaAs layer 14. In (b), the n-GaAs layer 17 is entirely grown on the P-AlxGa1-xAs layer 13, and Zn is diffused from above the n-GaAs layer 17 to form stripes for electrical inflow into the n-GaAs layer 17. Section 6 was formed. This is a Zn+ diffused stripe structure laser. <C>BaP-Ga
By providing an insulating film 23 such as a 5iOz film on the As layer 14, the stripe 16 for current injection is completely formed in the cita laser.

In each of a to C in FIG. 1, the stripe portion 16 limits the area where current flows, reduces the emission threshold of the semiconductor laser, and also reduces the active layer A7, Ga1, As layer (0
<y<x) The oscillation region in the active region 12 (hereinafter referred to as the active region 15) is completely restricted, and due to its shape effect, high-order transverse mode oscillation is completely suppressed, and single-transverse mode oscillation is realized. However, the above-mentioned method for completely fabricating the striped structure has the following drawbacks.

(1) In FIG. 1a, ions such as protons are accelerated by a total electromagnetic field and irradiated onto the fabricated double heterostructure semiconductor wafer. At this time, the irradiated area of the semiconductor wafer is damaged by the accelerated ions passing through it. Moreover, near the active region or near the proton irradiation region directly above the active region, the GaAs layer, Ga
A. In order to avoid damage to the crystal of the dAs layer, which would impair the electrical characteristics, optical characteristics, reliability, etc. of the semiconductor laser, it is necessary to perform annealing at a high temperature after proton irradiation. Not only will the number of steps be increased, but if a dopant with a high thermal diffusion coefficient such as Zn is present in the layer to be annealed,
These movements make it difficult to obtain a multilayer structure with good controllability of carrier concentration.

(2) In Figure 1, Zn diffusion is carried out at high temperature (7ccy℃~
The dopant in each layer is also diffused, causing the Pn junction interface to deviate from the designed position, and making it difficult to form the Pn junction as designed. (3) Figure 1C
Then, A%Ga1, the active region 15 in the As active layer 12
However, compared to the laser having the stripe structure shown in FIGS. 1a and 1b, there is a problem with the laser beam spreading. This is shown in Figure 1 a and b.
Compared to VC, the structure shown in FIG. The present invention provides a semiconductor laser device with a sufficient current narrowing effect.

Structure of the Invention In order to achieve this object, the semiconductor laser device of the present invention has three or more compound layers on an n-type compound semiconductor single crystal substrate, the uppermost layer being a P-type layer and including a double hemlock pattern. A semiconductor single-crystal layer is formed on the P-type layer, and a compound semiconductor single-crystal layer is formed on which 13 regions are of the P-type and other regions are of the n-type. This is due to the formation of a P-type compound semiconductor layer, which is crystalline and the rest is P-type polycrystalline. In this configuration
In this case, a stripe structure for current narrowing is formed by the above-mentioned part of the P-type compound semiconductor single crystal region and the above-mentioned part of the P-type compound semiconductor single crystal region. DESCRIPTION OF EMBODIMENTS DESCRIPTION OF EMBODIMENTS A semiconductor laser device can be easily obtained.An embodiment of the present invention will be described below with reference to all the drawings.FIG. 2 is a sectional view of a semiconductor laser device in an embodiment of the present invention. n-AlxG a 1x A s
Layer 11 , AlxGa1 yAs (0≦-y<x) layer 12 , P-AAxGal-xAsAs layer is formed, on which an n-GaAs single crystal layer selectively has a striped P-type diffusion region -27. 26, and further P-type diffusion region 2
On top of 7 is a P-GaAs single crystal layer 24. A P-GaAs polycrystalline layer 26 is formed on the n-GaAs single crystal layer 26.
The current is narrowed by the aAs single crystal layer 24 and the P-type diffusion region 27, and a low threshold value can be achieved.Next, a method for manufacturing the semiconductor laser device of this embodiment will be described. First, n-Alx (
ral-xAs layer 11, A 1yGa1. As layer (o
≦y'(x) 12, P-Agx(ral-x
AsAlB12 is grown as a single crystal, and an n-GaAs single crystal layer 26 is formed thereon. A P-GaAs polycrystalline layer 26 is grown. In this embodiment, the film thickness of the n-GaAs layer 26 is NO12pm, and the film thickness of the P-GaAs layer 25 is 0.5 μm. Regardless of the growth method, the polycrystalline layer is obtained by crystal growth while lowering the temperature of the growth substrate by several hundred degrees.

After crystal growth, after cleaning the growth surface with an all-organic solvent, the Ga
A part of the As polycrystalline layer 25 is formed into a single crystal in a stripe shape using a laser beam irradiation sound. , focus the Ar laser beam oscillating at 0.62 μm into a 6 μmφ spot (energy density ~io'W/ca)・T5 on the growth surface
Scan at mm/sea. Stripes for current narrowing as shown in FIG. 3 are formed with a pitch e of 250 μm. Note that the entire stripe may be formed using other heating means such as an electron beam.

Since the resistivity of the single crystal region 24 is about four orders of magnitude smaller than that of the polycrystalline region 25, current narrowing occurs in the single crystal region 24. Furthermore, in the n-GaAs crystal layer, the p-GaAs Immediately under the laser beam hitting the layer, Zn, which is a P-type dopant in the P-GaAs layer, has a large thermal diffusivity.
A portion of the diffused n, n-GaAs single crystal layer becomes a P-GaAs region 27 as shown in FIG.

At this time, the dopant may be of any type as long as it has a large thermal diffusion coefficient and becomes P type in GaAs. By this +, the P-GaAs single crystal region 24 and the P-Ad
The GaAs layer 13 is electrically connected to the P-GaAs region 27 via gold. On the other hand, in the n-GaAs region 26, P
- A Pn junction is formed at the boundary between the A7 GaAs layer 13 and the n-GaAs region 26, and when the semiconductor laser operates, it becomes reverse biased and no current flows. From the above, - P-GaAs
In addition to current constriction in the region 24, current constriction is also performed in the P-GaA5 region 27, and the effect is remarkable. It is also fully applicable to compound semiconductor materials.

Effects of the Invention As described above, the present invention has a stripe-shaped diffusion region on a double heterostructure, a single crystal region thereon, and a polycrystalline layer with 11iI planes on both sides. A semiconductor laser device with high performance and low threshold voltage can be realized.

[Brief explanation of drawings]

1a-c are cross-sectional views of a conventional semiconductor laser having a stripe structure, FIG. 2 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention, and FIG. FIG. 3 is a diagram for explaining a method of forming a structure. + 1o =-・n −GaAs base, 11°...n −
A, d XGa, -xAslii (first layer), 12=
-AlyGa1-yAs (0≦y<x), 13...
...P-AdxGal-xAs layer 14...P-
GaAsi, 16...active region. 16----- Stripe part, 17 =--n-Ga
As layer, 21°°"°°" high resistance region irradiated with protons, 22°" region, 26...n-GaAs layer. Name of agent: Patent attorney Toshio Nakao and one other person. Figure 1 Figure 2 Figure 7 Figure 3

Claims (1)

[Claims] On a semiconductor substrate of one conductivity type, a multilayer structure is formed with a semiconductor layer of a conductivity type opposite to the above-mentioned conductivity type as the entire top layer and a double heterostructure metal layer, and on top of the top layer. ,
The semiconductor layer having the - conductivity type having regions of the opposite conductivity type selectively in a stripe shape is formed, and further, the soil in the stripe-shaped opposite conductivity type regions is single crystal;
A semiconductor laser device characterized in that a semiconductor layer of opposite conductivity type, which is polycrystalline and has the same composition, is formed on top of the conductivity type semiconductor layer.