JPH01145882A - Short-wave semiconductor laser - Google Patents

Abstract

PURPOSE:To form an AlGaInPP type clad with a high carrier concentration without crystrallinity deteriorated, by disposing a Zn containing p-type GaAs layer with a concentration not less than a specific value of a carrier concentration adjacent to a p-type clad layer. CONSTITUTION:An Se doped GaAs layer 12, an Se doped (Al0.7Ga0.3)0.5In0.5P clad layer 13, a Ga0.5In0.5P active layer 14, a Zn doped (Al0.7Ga0.3)0.5In0.5P clad layer 15, a Zn doped GaAs 16, and an Se doped GaAs 17 are made to grow to thickness of 0.1-1mum on an n-type GaAs substrate 11 by the use of an organic metal vapor growth method. The growth temperature is 600-700 deg.C. When the p-type GaAs layer 16 and the p-type clad layer 15 are epitaxial growth layers having carrier concentrations 5X10<19>cm<-2> and 1X10<17>cm<-2> respectively, a series resistance of the element is as small as 3-6OMEGA, spite of the existence of a high resistance layer (p-type clad layer/several OMEGAs) in so that every element obtained continuously oscillates at room temperatures and does not deteriorate.

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a method for forming an ADG a I n PP P-type cladding having a high carrier concentration without causing such a decrease in crystallinity.

[Means for solving problems]

In the conventional laser structure, Zn is added to the P-GaAs layer in order to reduce the contact resistance between the P-GaAs layer and the P-type electrode.
When attempting to diffuse the ions, an element with low series resistance was obtained. This means that the diffusion of Zn is P-A Q G a I n P
This is thought to be due to the lower resistance of the cladding layer. It was found that the crystallinity of the cladding layer, whose resistance was lowered by this diffusion, was much better than that of a crystal grown epitaxially at the same carrier concentration.

The short wavelength laser of the present invention has (AlxGai-x) yI
nt-yP active layer and the active layer (A Q x'
G a 1-X' ) yI nt-yP (x'> x
), in which a Zn-containing p-type Ga having a carrier concentration of 5×1010 or more is adjacent to the p-type cladding layer;
It is provided with an As layer.

[Embodiments of the invention]

Comparative Example The crystal layer shown in FIG. 1 was grown under various conditions using organometallic vapor phase epitaxy. Using trimethylindium (hereinafter referred to as TMI n), triethyl gallium (hereinafter referred to as TEGa), and triethylaluminum (hereinafter referred to as TEAQ) as the raw material for the group ■ element, and PHaAsHa as the raw material for the group ■ element, n-type GaAs Se-doped GaAs layer 12 and Se-doped (A
lo, 7Gao, 3) o, aIno, 3P cladding layer 1
3, Gao, flIno, gP active layer 14, Zn doped (A Q 0.7G ao, a)o, aIno,
An r+P cladding layer 15, Zn-doped GaAs 16 and Se-doped GaAs 17 were grown to a thickness of 0.1-1 μm.

The growth temperature was 600-700°C.

First, to confirm the conventional technology, Se-doped n-type GaAs1
2 (same as 17) and (A Qo, 7Gao, a) o
, aI no, the carrier concentration of the in-type clad Jl 113 is set to I x 10 lacm-'', and the carrier concentration of the Zn-doped p-type Ga As layer 16 is set to I x 10 lacm-''.
"cm-", 5 Xl016'cm-", I X 1
0111>-” and Zn-doped (Aflo, 7G
A o, a) o, +s I no, +s The epitaxial growth layer of the P-type cladding layer 15 with a carrier concentration of 1×1017.5×10” and 1×10”8Q11-” was processed to fabricate a prototype laser with the structure shown in FIG. 2. Prototype production Of the lasers, the p-type GaAs layer 26 and the p-type cladding layer 25 have a low carrier concentration (I
-'' and 1 x 1017 dl-s), all of them exhibited continuous oscillation at room temperature.For the devices with low carrier concentration mentioned above, the contact resistance between the P-GaAs and the p-type electrode is large, and this causes continuous oscillation at room temperature. The series resistance of a device that continuously oscillated at room temperature decreases with the carrier concentration of p-type GaAs and p-type cladding, and this is because by increasing the carrier concentration, the main resistance component, p-type Ga
This is thought to be due to a decrease in the contact resistance between AS and the p-type electrode and the specific resistance of the p-type cladding layer. On the other hand, when the device was continuously operated at 25° C. and a 10 mW output for the purpose of examining the reliability of the device, it was found that the output decreased with the operating time, and this deterioration was significant in devices with a high carrier concentration in the p-type cladding. The reason for this is that defects such as crystal dislocations have occurred at the boundary between the active layer and the p-type cladding layer, based on cross-sectional observation of deteriorated devices, and the crystal defects in the p-type cladding layer caused by high doping are caused by the continuity of the device. This is thought to be due to the growth of the active layer due to the operation.

Example 1 P-type G a A 5 (1
6) And the carrier concentration of the p-type cladding layer 15 is distorted.
Example 1
A laser with the structure shown in FIGS. 2 and 3 was prototyped using a process similar to that shown in FIG. The series resistance of the element is 3 to 6 despite the presence of a high resistance layer (p-type rad layer/several ohms).
Ω, and even in the current narrow type shown in Figure 3, a low resistance element was obtained, indicating that Zn in the p-type GaAs layer diffused into the p-type cladding layer and lowered the resistance. it is conceivable that. All of the obtained devices emitted continuous light at room temperature, and unlike the conventional laser shown in Example 1, no deterioration was observed after several hundred hours. This is considered to be because the crystallinity of the P-type cladding layer with reduced resistance is of good quality, unlike the crystallinity of the epitaxial layer grown with high doping.

Furthermore, according to the above results, low carrier concentration (~I
Z through the p-type GaAs layer of
A similar effect is expected even if n-diffusion is performed, and ZnAsz
The effect of the present invention was experimentally confirmed by selective diffusion from a 5iaNa mask in nAs.

〔Effect of the invention〕

According to the present invention, the amount of Zn diffused into the p-type cladding layer can be controlled by the Zn concentration in the p-type GaAs layer.
This is effective in controlling the diffusion process by heat treatment in nAs and the comparison process.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of an epitaxial growth layer, and FIGS. 2 and 3 are cross-sectional views showing the structure of a semiconductor laser used to disclose the present invention.

Claims (1)

[Claims] 1. (Al_xGa_1_-_x)_yIn_1_-_
yP active layer and the active layer (Al_x'Ga_1_
-_x')_yIn_1_-_yP (x'>x) In a semiconductor laser comprising one or more P-type cladding layers selected from
×10^1^9cm-^3 or more Zn-containing p-type GaAs
Short wavelength semiconductor laser with layers. 2. The carrier concentration of the Zn-containing P-type cladding layer is 2×10
The short wavelength semiconductor laser according to claim 1, which has a wavelength of ^1^7 cm-^3 or less. 3. A short wavelength semiconductor laser according to claims 1 and 2, which uses GaAs as a substrate and has y in the range of 0.49 to 0.52.