JPH0376183A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To elevate a COD level and to increase an output by forming a first clad layer, an active layer, a second clad layer having a striped protruding section, a current blocking layer and a contact layer onto a substrate, doping a P-type dopant region to the striped protruding section and a section just under the protruding section in specified depth and bringing the conductivity type of the dopant region to a P type. CONSTITUTION:A P-Al0.5Ga0.5As second clad layer 4 has height h1 in the vicinity of a laser end-face, the inside thereof has a striped protruding section 5, in which h2h1<h2 holds, and thickness thereof is brought to (d) in regions except the striped protruding section 5. A doping of P-type impurity is performed deeper than a+h2+d and shallower than a+h1 when measured from the upper end section of the striped protruding section 5 in a P-type doping region 11, and the conductivity type thereof is made to be P. Currents are not made to flow through a region in which there is an N-GaAs current blocking layer 6 between a P side electrode 8 and an N side electrode 9, and are made to flow only through the striped protruding section 5 of the P-Al0.5Ga0.5As second clad layer, and electrons and holes injected to an N-Al0.155Ga0.35As active layer 3 are recombined, thus resulting in laser oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser device that performs high output operation.

[Conventional technology]

Figure 3 is a cross-sectional view showing a conventional semiconductor laser, and Figure E
Here, (1) is n-type (hereinafter abbreviated as n-) GaAs
Substrate - (2) is the n-A 16.6 G m 6.5 Aa first cladding layer provided on the n-GaAm substrate (1), (3) is the n-A 176.5 G m 6.5
A p-type (hereinafter abbreviated as P-) layer provided on the first cladding layer (2), Gao, 1 g As active layer, (4) P-AIo, 100 m.

,. A p-Al6.5Gao, 5As second cladding layer with striped convex portions (5) provided on the Am active layer (3), (6) is a P-Al6.5Ga6. The n-G a A a current blocking layer (7
) are n-GaAs current blocking layer (6) and p-Aji'6
．． , Ga. , p-GaAs contact layer provided on the striped convex portion (5) of the gAa second cladding layer (4), (8) is the p-side electrode (9) of nORw! very,
dO is the current path.

Next, the operation will be explained. P-side electrode (8) and n-side type i
During (9), a bias is applied so that the p-side electrode (8) becomes positive. n between the p-side electrode (8) and the n-side electrode (9)
- No current flows in the region where the GaAs current blocking layer (6) is present. The current flows through the n-GaAs 1l flow blocking layer (
6) is absent, i.e. p A16.6
Ga (14AII) flows only through the part where the striped convex portion (5) of the second cladding layer (4) exists. Current path α0
is shown in the figure. As the current flows, P ki
The electrons and holes injected into the o.15 Ga 6.g 6A s active layer (3) recombine and radiate. As the current level is increased, induced radiation begins, resulting in laser oscillation.

[Problem to be solved by the invention]

In a semiconductor laser device, when the driving current is increased, laser oscillation starts at a certain threshold current Ith, and when the current is further increased, the optical output increases accordingly. However, if the optical output exceeds a certain level (maximum optical output Pmax), the laser device will be destroyed. What is the cause of this?

The so-called COD (C
ataatrophie 0ptiaajJ Dama
ge).

In the conventional semiconductor laser device, in order to increase this COD level and increase the maximum optical output Pmax, p-AJcl
,+50m041"sThe film thickness d of the active layer is made thin, but the film thickness d of the active layer p-AIIO-)lGao-ag"
When the thickness becomes thinner than a certain value, the threshold current rth rapidly increases, and the drive current also rapidly increases, which causes an extremely serious problem in practical use.

This invention was made to solve the above-mentioned problems.
An object of the present invention is to obtain a semiconductor laser device that can increase the COD level and increase the output without making the active layer thinner.

[Means to solve the problem]

The semiconductor laser device according to the present invention has n A Ji 6.6G & 6.5 provided on an n-GaAs substrate.
A11 first cladding layer and the n-AJo, 6Gao4
A' 0.1 s provided on the first cladding layer
"o, stAg active layer and the n-Alo-tsG a
6, @6A s Provided in the active layer, the height is hl near the laser end face, and the height is smaller than hl in the central part.
The p-AJO,IGa(1, ,A
s an n-GaAs current blocking layer provided in a region other than the striped convex portion of the second cladding layer;
On the striped protrusions of the Ga,..., As second cloth layer and on the n-G layer As [p-G provided on the flow prevention layer]
It is composed of an a A s contact layer, and a p-type dopant is formed in the striped convex region and the region immediately below it.As measured from the upper end of the striped convex region, a + hz +
It is doped deeper than d (d is the thickness of the As active layer) and shallower than a + hl, and the conductivity type of this region is p-type.

[Effect]

Measured from the upper end of the striped convex portion in this invention: a + h! By doping deeper than + d and shallower than a+J, n −A16. HGa
The conductivity type of the O-115A" active layer is partially p-type rather than n-type, and remains n-type at the end facets. Therefore, light absorption at the end facets is suppressed, suppressing COD emission. Increase the maximum optical output Pmax.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a sectional view of the semiconductor laser device, and FIG. 2 is a sectional view taken along line AA shown in FIG.

In the figure, (1) to αG are the same as those shown in the conventional example of FIG. 3, so their explanation will be omitted.

P Ago-s"o-8" second cladding layer (4) is raised at a height hl- inside near the laser end face, (h, )
It has a striped convex portion (5) with a thickness of h, and the thickness of the area other than the striped convex portion (5) is d. Furthermore, the p-type doped region 0 is doped with p-type impurities to a depth deeper than 1k + 111 + d and shallower than a + J as measured from the upper end of the striped convex portion (5), and the conductivity type is p-type. It has become.

Next, the operation will be explained. A bias is applied between the paw pole (8) and the n-side electrode (9) so that the p-side electrode (8) becomes positive. No current flows in the region ξ where the n-GaAs current blocking layer (6) exists between the two electrodes.

The current flows in the area where the n-GaAs1i flow-blocking layer (6) is not present, which is completely P-P. , 5G11o, 5AI The current path α0 flowing only through the portion where the striped convex portion (5) of the second cloth layer exists is indicated by Eζ in the figure. As a current flows, the injected electrons and holes in nAl(3,15Gmg4BAa activity 11(3)s) recombine, causing induced radiation and leading to laser oscillation.Here, inside the laser, n-type impurities n-Alo by doping with
, +5Gao,ss'' active layer is changed from n type to n type.

〔Effect of the invention〕

As described above, according to the present invention, the active layer is -n-AI
GmAg active layer and p-AI inside! (1,, Ga
The height of the striped convex portion of the 6,5As second cladding layer is made smaller than that of the end face portion, and the n-type dopant region becomes a + h! + deeper than d and a+
Since it is made shallower than J, it becomes an n-type A#GaAs active layer inside and n-type at the end face, suppressing light absorption at the end face, and therefore having the effect of increasing the COD level.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a semiconductor laser device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A-A shown in FIG.
FIG. 3 is a sectional view showing a conventional semiconductor laser device. In Figure Iζ, (1) is an n-GaAs substrate, (2) is an n-GaAs substrate, and (2) is an n-GaAs substrate.
-A16-5G,. , 5As first cladding layer, (3) n AA'o, 150ao, s 3As active layer (4)
is p A Io, 5G a 6.6A s 2nd Cla-V
layer, (5) is a striped convex portion, (6) is n-GaA
g lI flow stop layer (7) is a p-GmAs contact layer, (8) is a P-side electrode, (9) is a Dam pole, αO is a current path, and 0 is a P-type doping region. In addition, in FIG. 1, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] an n-type AlGaAs first cladding layer provided on the n-type GaAs substrate; an n-type AlGaAs active layer provided on the n-type AlGaAs first cladding layer;
Provided in the aAs active layer and has a height of h_1 near the laser end face.
, a p-type AlGaAs second cladding layer whose central part has a height h_2 smaller than h_1, has a striped convex part, and has a thickness of a except for the striped convex part;
an n-type GaAs current blocking layer provided in a region other than the striped convex portion of the n-type AlGaAs second cladding layer, and an n-type GaAs current blocking layer provided on the striped convex portion of the n-type AlGaAs second cladding layer and on the n-type GaAs current blocking layer. p-type GaAs provided
A p-type dopant region is doped in the striped convex region and the region immediately below it, deeper than a+h_3+active layer thickness d and shallower than a+h_1, as measured from the upper end of the striped convexity. A semiconductor laser device characterized in that the conductivity type of the region is p-type.