JPH01196890A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor laser device oscillated at a fundamental transverse mode by a low threshold current value by effectively injecting electrons and holes to an active layer having striped width of approximately 2mum or less. CONSTITUTION:A recessed section is formed to a substrate 11, and a GaAs buffer layer 12, a P-type AlxGa1-xAs clad layer 13, a multiple quantum well type active layer 14, an N-type AlxGa1-xAs clad layer 15 and an N-type GaAs contact layer 16 are grown into the recessed section. An N-type electrode 19 and P-type electrodes 18 isolated to a striped shape are formed respectively in an ohmic manner. Both electrons and holes in carriers are injected effectively to the multiple quantum well type active layer 14 having striped width of 2mum, and laser beams are also confined effectually into a region having striped width W. Accordingly, a semiconductor laser device oscillated at a fundamental transverse mode at a low threshold current value is acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor laser device used as a light source for various electronic devices.

Conventional technology When integrating semiconductor lasers and electronic circuits in a hybrid or monolithic manner, the fact that the semiconductor laser wafer has a planar surface and a planar electrode configuration increases the speed and reliability of the integrated device. This is important from the viewpoints of maintaining properties and facilitating the process of connecting elements.

FIG. 2 shows a conventional example. (1sae Autumn Academic Conference Proceedings of the Japan Society of Applied Physics 2 Ryoa-T-B, p. 155 Kumauchi et al., “Laterally Injected Laser (1) - Basic Structure”)
High resistance A I G on semi-insulating Ga A s substrate 1
a As layer 2° multi-quantum well type active layer 6. High resistance A
After forming the IGaAs layer 6 and the GaAs contact layers 7 and 8, a p-type diffusion region 3 and an n-type diffusion region 4 are formed of Zn and Si, respectively. n-type GaAs contact layer 7 and p5G left by microfabrication
On the aAs contact layer 8, an n-elevation j electrode 9 and a p-side electrode 10 are formed ohmically. In the fabricated device shown in FIG. 2, carriers are injected from the n-type diffusion region 3 and the n-type diffusion region 4 into the multi-quantum well type active layer 5 with a stripe width W, and are recombined, resulting in laser oscillation. . The laser light is effectively confined in the multi-quantum well type active layer 5 having a stripe width W. In the stacking direction, adjacent high resistance AlGaAs
The forbidden band width of claddings a2 and 6 is sufficiently large (the active layer is larger), and in the direction perpendicular to the stacking direction, the layer adjacent to the active layer is decontaminated from the quantum well structure due to the disordering of Zn and Si. This is because the optical waveguide with the stripe width W is formed. As a result, W = 0.571m
A laser that oscillated with high efficiency at a current value of 30 mA was obtained.

Problems to be Solved by the Invention However, in the above structure, the stripe width W is 1.5.
If it exceeds 1 tm, there will be disadvantages such as an increase in the threshold value (more than double) and a decrease in efficiency (less than '/). This is thought to be due to the injection of carriers from each diffusion layer into the quantum well type active layer in the lateral direction, and as the stripe width increases, the concentration distribution of electrons and holes within the stripe becomes more pronounced. This is thought to be the result of a decrease in the probability. Furthermore, it is difficult to obtain a stripe width W of about 0.5 μm with good reproducibility using Zn or Si diffusion prosthesis.

In view of the above drawbacks, the present invention provides a semiconductor laser device that effectively injects electrons and holes into an active layer with a stripe width of about 2 μm or less, and as a result, oscillates in a fundamental transverse mode with a low threshold current value. .

Means for Solving the Problems In order to solve the above problems, a semiconductor laser device of the present invention includes a semi-insulating substrate having a recess, and a striped multilayer thin film having a width narrower than the recess. comprises at least an active layer and a cladding layer adjacent to the active layer having a wider forbidden band width than the active layer, and the active layer has a multiple or single quantum well structure, and the striped region of the recess In the other regions, a multilayer thin film including a double heterojunction of one conductivity type is formed, and further, adjacent to the multilayer thin film, a layer of the same conductivity type as the multilayer thin film is formed on the substrate side and on the side opposite to the striped multilayer thin film region. forming a stripe-like electrode on the surface of the stripe-like region, one recess narrower than the stripe width, and at least one stripe-like electrode separated from and parallel to the stripe-like electrode on the multilayer thin film region of one conductivity type.
It is constructed by having three or more striped electrodes.

Function: With this configuration, carriers can be injected efficiently, and a semiconductor laser device that oscillates in the fundamental transverse mode with a low threshold current value can be realized.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention, and the operation results of the semiconductor laser device configured in this manner will be described below.

As the substrate, a semi-insulating GaAs substrate 11 is used, as shown in FIG. A concave portion is provided in the substrate 11, and G is grown in the concave portion by selective epitaxial growth using the MOCVD method.
a As buffer layer 12. p-type Al, Ga1-, As
Cladding layer 13. Multi-quantum well type active layer 14. n-type A/
! xGa1-xAs cladding layer 15. n-type GaAs m
l:/tact layer 16, 111 m and 1.27, respectively
zm, 0.171m (4 in GaAg well,
4 wells, 100 people, bud μf.

A ly G a 1y As barrier, 1.5 layers,
12OA layer thickness (Q (7(X > ), 1.27z
m, 0.5 layers are grown to a thickness of 1 m. Growth temperature is 75
0°C, growth rate 31 trn/hour.

The V/I ratio was 60. Leaving the active layer width W, Zn is diffused as shown in FIG. 1, and then an n-side electrode 19 and a p-side electrode 18 separated into stripes are formed ohmically.

The fabricated semiconductor laser has a stripe width W=α5 It
Fundamental transverse mode oscillation was performed at a threshold current value of 30 mA or less at m to 2.01 t m. In terms of current vs. light output characteristics as well, good linearity was obtained up to 10 mW, and the decrease in efficiency due to the stripe width W was less than 10%.

From the above results, it can be seen that carriers, both molecules and holes, are effectively injected into the multi-quantum well type active layer with the stripe width W, and the laser light is also effectively confined in the region with the stripe width W. The reason why the region of the stripe 4W becomes an optical waveguide so that the confinement of the laser light occurs is because the quantum well layer in the adjacent Zn diffusion region changes to a mixed crystal composition due to the disordering of Zn. it is conceivable that.

In addition, in this example, Ga, As-based, AlGaA
Although the s-based semiconductor laser has been described, the present invention can be similarly applied to semiconductor laser devices made of compound semiconductors including InP-based and other mixed semiconductor lasers.

Effects of the Invention The present invention has a planar surface and electrode structure that can efficiently inject carriers into the active layer, oscillates in a fundamental transverse mode with a low threshold current, and is suitable for integration with electronic circuits. It provides the structure of a semiconductor laser device, and its practical effects are remarkable.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a semiconductor laser device according to an embodiment of the present invention;
FIG. 2 shows a cross-sectional view of a conventional semiconductor laser device. 1.11...Semi-insulating GaAs substrate, 2
...High resistance AIGAs layer, 3...
...p-type diffusion region, 4...n-type diffusion region,
5,14...Multiple quantum well type activation, 6-0.
, ++, -6 resistance A I Ga As layer, 7---
--- N-type GaAs: 1 contact layer, 8...
P-type GaAs contact layer, 9°19...
...N-side electrode, 10.18...P-side electrode, 12
・・・・・・G a A s Ha Sofa Layer, 13...
... p-type AlGaAs cladding layer, 15-n type A
lGaAs cladding layer, 16...n type G
aA s contact layer, 17...p5Zn diffusion region, W...stripe width. Name of agent: Patent attorney Toshio Nakao and 1 other person71
--'t & bottle a (qa As substrate 72, -C
raAs t< buffer layer/3-- P'JLA1(ra
As Crat Layer/4--・Multiple Quantum Well Rokuji Drinking Viewpoint 15--- Type 72 A1ξAs7 Rad 1, 萱#)---
-n-type GaAs: I>9'7 t41'1---PriZ
n Diffusion area 1B ---P I! Lipe 1 food Figure 1 1'1-77 messenger jt @ 7--Ki insulating column CraAs substrate 2-°° elevation hole AI! 6tzAs layer 3--P type s, Scattered horizontal bar 4--71 type #,, contact area S--multiple doji kita air temperature] 1 6 =-at resistance AI Cra AsM9--n type electrode 10...-P type electrode

Claims (1)

[Claims] In the recess of a semi-insulating substrate having a recess, an active layer having a quantum well structure and a cladding layer adjacent to the active layer having a bandgap width larger than that of the active layer are included in a stripe shape having a width narrower than the width of the recess. A multilayer thin film is formed, and a multilayer thin film including a double heterojunction of one conductivity type is formed in a region of the recess other than the striped multilayer thin film, and further, a multilayer thin film including a double heterojunction of one conductivity type is formed adjacent to the multilayer thin film except for the striped multilayer thin film region. The region of one conductivity type is formed, and the stripe-shaped multilayer thin film has striped electrodes having a width narrower than the stripe width on the surface of the striped multilayer thin film, and striped electrodes on the multilayer thin film of one conductivity type. Semiconductor laser equipment.