JPH03161988A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To prevent P from leaving the crystal surface of A GaInP at the time of re-growth, and improve the interface quality of a constriction layer, by forming an interface protecting layer between the etching surface of a clad layer of a stopper layer and a GaAs current constriction layer. CONSTITUTION:Double hetero junction structure is formed by crystalgrowing the following in order on an n-GaAs substrate 1; an n-GaInP buffer layer 2, an n-AlGaInP clad layer 3, a GaInP active layer 4, a p-AlGaInP clad layer 5, a p-GalnP band gap relieving layer 6, and a p-GaAs contact layer 7. An SiO2 film 13 is formed; by using it as a mask, the layers 7, 6 and a part of the layer 5 are etched; thus a mesa type protrusion 14 is formed. While the SiO2 film 13 is used as a mask as it is, an n-GaIn interface protecting layer 12 and an n-GaAs current constriction layer 8 are grown. The film 13 is eliminated, a p-GaAs contact layer 9 is grown, and a p-side electrode 10 and an n-side electrode 11 are vapor-deposited.

Description

[Detailed description of the invention] [Field of application in industry] The present invention provides a ke(k>
1. The present invention relates to an nP-based visible light semiconductor laser device.

[Conventional technology]

Conventionally, this type of semiconductor laser device has been disclosed, for example, in Japanese Patent Application Laid-Open No. 1986-
As shown in Publication No. 200786 (■oIS3/18), AJGa ]. n P type n
The type cladding layer, the active layer, and the p-type cladding layer are sequentially elongated to form a double heterojunction structure, and the p-type cladding layer is etched into a mesa shape or structure, and an n-type GaAs current narrow single layer is re-etched on this. It is made to look dignified.

That is, FIG. 5 shows the element structure of a conventional semiconductor laser device. (1) is an n-type GaAs substrate, and on this substrate (1) is formed an n-type GalnP 7 layer f21.
, n-type AgGalnP I land layer (3),
The GalnP active layer (41p5A/'GalnP cladding layer (51), p-type Gal.nP band Ganop relaxation layer (6) and p-type GaAs contact layer (7) are crystallized in sequence, and the active layer (4) and both surfaces thereof A double heterojunction structure is formed by the junction cladding layers (3) and (51), respectively.

Note that the relaxation layer (6) is provided to alleviate the discontinuity of the band gap between the cladding 11+51 and the contact layer 7).

+8+ is an n-type GaAs current confinement layer, which is re-lengthened after etching the contact layer ``7'' l relaxation layer (6) and cladding layer (5) into a mesa shape.

(9) is P-type GaAs contact layer, no is Au-C
r alloy P side electrode, 01) (d Au-Sn-
This is an n-side electrode made of an Or alloy.

By the way, in the structure described above, the current confinement layer (8)
When re-lengthening, the Ag(ialnP crystal of the cladding layer (5) is exposed on the etched crystal surface, so when the temperature rises due to re-lengthening, P evaporates and leaves the crystal surface.
This has the disadvantage of causing damage to the crystal surface.

For this reason, in the above-mentioned publication, a flow of PHs (phosphine) is flowed during temperature rise to prevent the separation of P as the temperature rises, and group V gas is added from PHa to A8H8 immediately before the GaAs precipitate.
(Arsine) (7) A method is adopted in which the organic metal gas of (4a) is introduced to elongate the crystals of (4aAs).

[Problem to be solved by the invention]

However, in the method described above, P
Although the separation of P can be prevented, when switching the V group gas, P is removed from the crystal surface, and along with this, A7' (
4a Etched surface of 1nP crystal and elongated CiaA
Defects are introduced at the interface with s, resulting in an adverse effect on the life of the element.

The present invention has been made in consideration of such problems of the prior art, and its purpose is to solve
AeGa In with ia As-based current confinement layer
In a P-based visible light semiconductor laser device, AI during re-lengthening
! Preventing the separation of P from the GaInP crystal surface,
The objective is to improve the interface of the aAs-based current confinement layer.

[Means to solve the problem]

In order to achieve the above object, the semiconductor laser device of the present invention includes an AeGaInP-based double heterojunction structure formed by a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer. , and a current confinement layer is provided between the GaAs-based first conductivity type current confinement layer formed in the second conductivity type cladding layer and the second conductivity type cladding layer or the etching stopper layer of the cladding layer. They have the same conductivity type (A4x
Ga+-x)o. 51 no. 5P (0,?x(1)
system crystal or Gal. It is characterized in that an interface protective layer made of nAsP-based crystal is formed.

[Effect]

In the semiconductor laser device configured as described above,
A first conductive layer containing P between the GaAs-based current confinement layer of the first conductivity type and the etched surface residue of the second conductivity type cladding layer or, if a Nutopper layer for etching is formed in advance on this Nutopper layer, is formed. Since the structure is such that a conductive interface protective film is formed, when the current narrowing layer 9 is re-lengthened after etching the cladding layer, for example, Pus gas is flowed while the temperature is raised to increase the crystallization of the cladding layer and the stopper layer. In addition to preventing P from leaving the surface, with this gas flowing (Aex GaI
-x) o. s 1 no. 6P series or GalnAsP
Therefore, just before a certain length of GaAs for the current confinement layer, group V gas is changed from PHa to As.
Even if you switch to f{a, the cladding layer or stopper layer p
P is no longer detached, and defects are prevented from being introduced into the re-elongated interface.

〔Example〕

One embodiment of the present invention will be explained using FIGS. 1 to 4.

FIG. 1 shows the device structure.The difference from the conventional device shown in FIG. 5 is that p-type Al! n-type G re-lengthened after etching the GalnP cladding layer 151 etc.
An n-type GalnP ((AexGa+-
x)o. 51 no. 5P + x = 0) is formed with a thin interface protective layer a2.

FIGS. 2fa) to 2fdl show the manufacturing process of the IitI element, and the manufacturing method will be explained below using this.

As shown in figure fa), n-type G
a I nP huffer layer f21, n-type AgCial
nP clad 7d layer (3). GalnP active layer (41
．． 1) Type Al! GalnP I rad layer 151, p-type GalnP bandgap relaxation layer +61 and p-type GaA
The s-contact layer f71 is successively crystallized to form a double heterojunction structure.

Next, as shown in the same figure, a GaAs-based contact layer (7
) using a sulfuric acid-based etching solution, and etching the AgGaInP-based relaxation layer (6) and the p-type TALLAD layer C51 using an HBr (hydrogen bromide)-based etching solution. Etching is performed so that about 0.8/lm remains to form the mesa-shaped convex portion 04).

Next, as shown in the same figure (cl), the FLn type Gal.nP interface protection layer 02 and n
A type C4a As current confinement layer (8) is grown at a crystal growth temperature of 650°C.

When re-elongating with Pf{s, Ganu of Pf{s is introduced at the time of temperature rise,
After reaching a predetermined temperature, the G
The AlnP crystal is lengthened to a certain extent to form an interface protective layer α.

Furthermore, the V group gas is switched from PHs to AsHa, and the GaAs crystal is elongated on the interface protection layer 02, thereby creating a current confinement layer +8
form 1.

Thereafter, the 8i02 film surface was removed using an HF (hydrogen fluoride)-based etching solution, and the p-type GaAS contact layer (9) was lengthened to a certain extent, and the p-side electrode layer and n Side electrodes (II) are respectively deposited to complete the device of FIG.

Figure 3 shows the results of a life test of the semiconductor laser device fabricated in this manner at 50°C and output 3m WoAPC (Auto Power Controller) operation. It is clear that the device of the present invention shown by the solid line can have a longer lifespan compared to the conventional structure shown by the broken line.

Incidentally, since the interface protective layer q is formed thinly, there is almost no problem of temperature rise due to an increase in thermal resistance.

By the way, Gal. Since the energy gap of nP crystal depends on temperature as shown in Figure 4, Ga
l. For example, if a certain long temperature of the nP active layer (41) and a certain long temperature of the n-type (JalnP interface protection layer a) are set to 7 as in the example,
By changing the temperature to 20°C and 650°C, the energy gap can be made different, that is, the energy gap of the interface protective layer 0 can be made smaller. It functions as a light absorption layer, making it possible to obtain a transverse mode control type semiconductor laser device.

In the above embodiment, the active layer (4) is made of Gal. nP
was used, the interfacial protective layer 0η was made n-GalnlF, and the long temperature was changed to make the energy gap of the interfacial protective layer α smaller than that of the active layer (4).
The active layer (4) is (AeyGa+-y)o. 5'no,s
If r (0≦y×1), the interface protective layer 0
(#x 01-gc) 0.5' no. If it is composed of 6 P and its Ae group weight X is X≦y, then the active layer (4)
It is possible to obtain an interfacial protective layer a having an energy gap equal to or smaller than the energy gap of a.

In addition, in the example, when the temperature rises due to regrowth, etc.
This is a case of preventing the separation of P from the GaInP crystal surface.
In order to prevent the separation of both group Ⅰ elements As and I' from each crystal surface, Asf{
It is sufficient to introduce S and PHB at the same time, and in this introduced state, cladding layers etc. are etched and the interface protective layer of the GalnAsP crystal is lengthened to a certain extent.

Furthermore, when forming a stopper layer (low, J7 group or p-type Al!GalnP) for stopping etching on the P-type cladding layer (5), an interface is formed at 4 between this cladding layer and the current confinement layer. By forming the protective layer, separation of P from the surface of the stopper layer can be prevented.

〔Effect of the invention〕

As described above, the semiconductor laser device of the present invention has a structure in which an interface protective layer is formed between the etched surface of the cladding layer 1 or the stopper layer and the GaAs current confinement layer, so that re-orientation is not necessary. It is possible to prevent P from leaving the AeGaInP crystal surface over a long period of time, improve the interface between the long crystals, extend the life of the device, and increase reliability.

[Brief explanation of the drawing]

1 to 4 show a semiconductor laser device according to the present invention.
Examples are shown, and Fig. 2 is a cross-sectional view, and Fig.
) are cross-sectional views of different states showing the manufacturing process, respectively.
The figure is a current characteristic diagram showing the element life test results, and Figure 4 is a Ga
FIG. 5 is a characteristic diagram showing the long-term temperature dependence of energy pg in an lnP crystal, and is a cross-sectional view of a conventional example. (3) ・= n if'J AeGalnl' I
Ranod trunk, (41 =- Gnl.nI' active layer, +5
1-p type AeGalnP cladding, it'll ・
-n-type C4*AS current confinement layer, 0ka...n-type rJal. nl' interface protection.

Claims (1)

[Scope of Claims] 1. A double heterojunction structure is formed by a first conduction type cladding layer, an active layer, and a second conduction type cladding layer, and the second
In an AlGalnP visible light semiconductor laser device comprising a GaAs-based first conduction type current confinement layer in a conduction type cladding layer, the current confinement layer and the second conductivity type cladding layer or an etching stopper layer for the cladding layer; has the same conductivity type as the current confinement layer (Al_xGa_1_-_x
)_0_. _5In_0_. A semiconductor laser device characterized by forming an interface protective layer made of a _5P (0≦x<1) crystal or a GaInAsP crystal.