JPS62249495A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To improve electrical and optical characteristics and make manufacture easy by a method wherein a laminated structure is composed of a semiconductor layer which has an optional forbidden band width and semiconductor layers which have larger forbidden band widths than the former one which hold the former one between them and the laminated structure is made to grow successively on a semiconductor substrate which has electrical and optical properties different from those of the semiconductor layers and the laminated structure and the semiconductor substrate are unified. CONSTITUTION:An N-type Ga1-xAlxAs cladding layer 2, an N-type or P-type Ga1-yAlyAs active layer 3 (x>y) and a P-type Ga1-xAlxAs cladding layer 4 are successively formed on an N-type silicon crystal substrate 1 by MO-CVD or MBE. Then an oxide film 5, which has a predetermined stripe shape aperture, is formed on the P-type Ga1-xAlxAs cladding layer 4 by CVD and is operated as a current limiting layer. Then metal electrodes 6 are formed on the silicon crystal substrate 1 and on the oxide film 5 by vacuum evaporation and the whole structure is cleft into predetermined dimensions to form a semiconductor laser. With this constitution, highly accurate alignument between the laminated structure and a submount can be eliminated and the productivity and yield of the semiconductor device can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor laser device, and in particular to providing an inexpensive semiconductor laser device by integrally forming a semiconductor laser chip and a heaton/liquid. .

[Conventional technology]

Semiconductor laser devices used as light sources for compact discs, video discs, etc. have conventionally been manufactured in a first-order manner. In other words, if we take a GaAs z-based semiconductor laser device as an example, a type Ga1-xAL is formed on a GaAs substrate.
xAz cladding layer, type or p type Gα+-yfiJ,
yAz active layer Cs:>y) rp type Ga + -z An
x/(Jl cladding layer, F& type GaAz cap layer are successively grown using the liquid phase epitaxial growth method, then P type GcL, P type GcL,
-EM Process A: A semiconductor laser tip is completed by providing a diffusion layer deep enough to reach a part of the cladding layer and depositing electrodes on the surfaces of the square-shaped GaAs substrate and the square-shaped GaAs cap. Thereafter, the semiconductor laser chip is soldered to a silicon submount or heat exchanger to complete a semiconductor laser device. Incidentally, examples related to this type of device include Japanese Patent Publication No. 49156/1982, Japanese Patent Publication No. 22428/1982, and Japanese Patent Publication No. 32518/1989.

[Problem that the invention seeks to solve]

In the above prior art, type or p type Gα1-yfi
iyAz active layer sandwiched between Le type or P type Ga + -z
A stack consisting of Alz, 4# cladding layer must be grown on a very expensive square GaAJ-substrate.

In addition, the semiconductor laser tip, which has been subdivided into 400 μn x 3 QQ μm, is placed on a silicon submount or a heat sink so that the valve opening surface (light emitting surface) of the semiconductor laser chip and the submount or the end surface of the heat sink coincide and are parallel to each other. You have to make solder connections like this.

The light emitted from the valve opening surface of the semiconductor laser tip is diffusely reflected on the submount S or the heat sink surface, causing a problem in which the emitted beam shape and its direction change. cannot exhibit typical optical properties. Moreover, these have become the biggest bottleneck in improving yield, streamlining, and lowering costs.

An object of the present invention is to provide a new semiconductor laser device that has excellent electrical and optical characteristics, is easy to manufacture, and is inexpensive.

[Means for solving problems]

The above object is to create a laminate structure in which a semiconductor layer having an arbitrary forbidden band width is sandwiched between semiconductor layers having a forbidden band width slightly larger than the above-mentioned forbidden band width, which is electrically and optically different from the semiconductor layer. This is achieved by successively growing semiconductor substrates with different properties and integrally forming the above-mentioned laminate structure and the semiconductor substrate.

[Effect]

The semiconductor substrate is made of a material that has different electrical and optical properties from the monolithic structure and has excellent thermal conductivity.

By integrally forming the laminate structure on the semiconductor substrate, the semiconductor substrate functions as a submount or a heat sink. As a result, in a semiconductor laser device in which a laminate structure and a semiconductor substrate are integrally formed, there is no need for a submount or high precision alignment with a heaton/retard. Light emitted from the valve opening surface of the semiconductor laser device can exhibit good electrical and optical characteristics without being affected by the submount or heat sink surface.

〔Example〕

Hereinafter, one embodiment of the present invention will be described using a silicon substrate and GaMAs.
The case of a system growth layer will be explained using FIG. 1.

Le-shaped silicon crystal substrate (thermal conductivity 1.5 W/1., , z ) that exhibits thermal conductivity that is one order of magnitude better than GaAs crystal (thermal conductivity 0.8 W/cm ・K ) 1
On top, there is a Le-type Ga1-xAlzAz cladding layer 2 and a Le-type or P-type Ga + -y M,'/Ax active layer 3 (
x>y> and the P-type Ga1-s:Als:As cladding layer 4 using the well-known No-CVD method (JfgtaLO
r, quanic Chemical Vapor De
position) or MBE method (Mo1ecu
lar Bgam Epitas:y).

Continuously layer. Next, the p-type Gα1-xfiJt
seAzri,? An oxide film 5 having predetermined stripe-shaped openings is provided on the RAD layer 4 by the CVD method to function as a current limiting layer. Thereafter, a metal electrode 6 is deposited on the silicon/crystal substrate 1 and the oxide film 5 using a vacuum evaporation method, and the valve is opened to a predetermined dimension, thereby completing a semiconductor laser device.

The current limiting layer formed using the oxide film 5 is formed by forming an insulating region on the P-type Gα+ −x Mx Aj cladding layer 4 excluding predetermined striped openings by irradiating protons or the like.

This can also be achieved by providing the layer to a depth that reaches a part of the silicon crystal substrate 1.

≠㉟#ヰ Note that Ga was grown with the composition ratio 2 and crystal growth conditions optimized between the above-mentioned laminate structures 2 to 4 and the silicon/substrate 1.
4-Z By inserting the AlzAz buffer layer, the cladding layer is free from crystal defects (in many cases misfit dislocations) that occur due to the difference in lattice constant from the silicon substrate.
can be relieved.

Reliability can be improved.

On the other hand, even if the structure of the 1Gα1-1N, zAz buffer layer is changed to an amorphous GσAt crystal by changing the crystal growth conditions (lowering the growth substrate temperature, etc.), it is also possible to change the structure of the 1Gα1-1N, zAz buffer layer to an amorphous GσAt crystal by changing the crystal growth method and forming at least two or more layers of GaAs and AIAJ. Even with a superlattice layer structure consisting of the above-mentioned Gα1-zMzA buffer layer, it is possible to prevent crystal defects from being introduced into the active layer, as in the case of the Gα1-zMzA buffer layer.

Hereinafter, a modification of the present invention will be explained using FIG. 2 and FIG. 3.

In Figure 2, GaAslB crystal (thermal conductivity o, s
r-type silicon crystal substrate (thermal conductivity 1.5 W/cyt-g) that exhibits better thermal conductivity than rr/,,z')
11, FL type Ga1-zM, zAtAt rose 2 (0≦2≦1) and % n-type Ga1-yA1yAz cladding layer 13, R-type or P-type Ga1-xNLxAz active layer 14 (r<y) and tp. Type Ga1-ylJ, yAz
The cladding layer 15 is formed using the well-known MO-CVD method (
MetalOrganic-Chemical Va
por Dmpozition) or MBE method (
MoLgcttLar Bgam Epitaxy)
are used to stack them continuously. Next, the above p-type Gα+−
An oxide film 16 having predetermined stripe-shaped openings is formed on the yNlyAz cladding layer 15 by a normal CVD method (Chemical CVD method).
After forming the silicon crystal substrate 11 and the P-type Ga 1-AlyAz cladding layer 1 including the oxide film 16
A metal electrode 17 is deposited on the layer surface 5 and the layer surface 5 using a vacuum evaporation method. Next, the predetermined dimensions (for example, 400 μm x 300
A semiconductor laser device is completed by interosseous separation in micrometers (resonator length).

The silico/substrate 11 and the Le-type GαI -z AAz
7Cy Due to the lattice constant difference with the buffer layer 12, crystal defects such as misfit dislocations are caused by the
AAz At is introduced into the buffer layer 12, but depending on the substrate temperature of the silicon substrate 11 or the Le type Gα1-zA1z
By appropriately selecting the composition, crystal growth rate, etc. of the Aj buffer layer 12, misfit dislocations are
x fiJlx Ax can be prevented from entering the active layer 4.

In addition, in the above modification, the le-type Gα+ −Z 7Vl
If the crystal growth conditions for the z At buffer layer 12 are appropriately selected, amorphous QaAz can be grown. By using the amorphous GaA z layer as a buffer layer, introduction of crystal defects from the silicon substrate 11 can be prevented.

FIG. 3 is an explanatory diagram showing another modification, in which at least two or more GaAs layers and uAz layers are alternately and continuously grown instead of the L-type Gα1-zklzAi buffer layer 120 described in the modification. A superlattice layer 19 is formed. Misfit dislocations from the silicon/substrate 11 are relaxed at each monoatomic layer interface of the superlattice layer 19 and do not propagate to the Le-type or p-type Gα1-xA1xAz active layer 14 provided on the superlattice layer 19. .

〔Effect of the invention〕

According to the present invention, the Le-type or p-type Gα1-yAlyAz
The laminate structure consisting of the Le-type or P-type Gα+-xM and xAz cladding layers sandwiching the active layer can be integrally formed on a silicon crystal substrate with good thermal conductivity that also serves as a submount or a heaton. High-precision alignment between the laminate structure and the submount is no longer necessary, and the productivity and yield of semiconductor laser devices can be greatly improved. In addition, by using a large-area, inexpensive silicon crystal as the substrate instead of a very expensive GaAs crystal,
This has the effect of significantly reducing the cost (about 1/10) of the semiconductor laser device.

Furthermore, a Le-shaped Gα
+-zMzAz layer or amorphous GaAt layer or at least two or more GaAs layers and 74 Az J
By providing a superlattice layer consisting of @ as a buffer layer, it is possible to prevent misfit dislocations from being introduced into the laminate structure due to the difference in lattice constant between the laminate structure and the silicon substrate, resulting in high reliability. It is possible to exhibit electro-optical properties having the following characteristics.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a semiconductor laser device illustrating an embodiment of the present invention. FIGS. 2 and 3 are cross-sectional views of a semiconductor laser device for explaining the present invention in detail. 1......Silicon crystal substrate 2...
......R type Gα1-xk1scAz cladding layer 3...R type or P type Gα+
-, Al y Az active layer 4...
...P-type Gα1-xAlxAz cladding layer 5...
......Oxide film 6...Metal electrode 11...Silicon substrate 12...Le W Ga+-zMzAz /
Fufa layer 13... Le type Gα1-yAl
yAs cladding layer 14... Le type or P
Type Ga + -x AJlx At active layer 15...
...... p W Ga1-yNl, yAz cladding layer 16 ...... Oxide film 17 ...... Electrode

Claims (1)

[Claims] 1. A stacked structure in which a semiconductor layer having an arbitrary forbidden band width is sandwiched between semiconductor layers having a forbidden band width larger than the above-mentioned forbidden band width is electrically different from the above-mentioned semiconductor layer. A semiconductor laser device characterized in that it is continuously grown on semiconductor substrates having different optical properties. 2. The semiconductor laser device according to claim 1, further comprising a buffer layer provided between the laminate structure and the semiconductor substrate. 3. The semiconductor laser device according to claim 2, wherein the buffer layer is made of amorphous GaAs. 4. The semiconductor laser device according to claim 2, wherein the buffer layer is a stack of at least two GaAs or AlAs superlattice layers.