JPH0533552B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical semiconductor device, and more particularly to a method for manufacturing a Ga _1-x AlxAs optical semiconductor device having an internal current confinement layer.

BACKGROUND ART In a Ga _1-x AlxAs semiconductor laser device having an internal current confinement layer, the current confinement layer is usually made of N-type GaAs or Ga _1-x AlxAs. For example, if the current confinement layer is made of P type, the diffusion of minority carriers will be long, so
A relatively thick current confinement layer of about 10 μm is required.
On the other hand, if the current confinement layer is N-type, the diffusion length of minority carriers is generally short, so the current confinement layer can be made thinner. For example, if the carrier density is 5×
A GaAs current confinement layer of 10 ¹⁸ cm ^-3 can perform current confinement if the thickness is 0.3 μm or more. For this reason, a semiconductor laser device having an internal current confinement layer has the shapes shown in FIGS. 3 and 4. In the prior art shown in FIG.
A GaAs current confinement layer 2, a P-type GaAlAs cladding layer 3, a GaAlAs active layer 4, an N-type GaAlAs cladding layer 5, and an N-type GaAs cap layer 6 are laminated in this order by liquid phase growth.

Furthermore, the semiconductor laser device shown in FIG.
On the N-type GaAs substrate 7, an N-type GaAlAs cladding layer 8, a GaAlAs active layer 9, a P-type GaAlAs cladding layer 10, an N-type GaAs current confinement layer 11, a P-type
The GaAlAs clad layer 12 and the P-type GaAs cap layer 13 are formed by metal organic chemical vapor deposition (MOCVD).
The layers are formed in this order.

As is clear from the illustrations in FIGS. 3 and 4, in conventional semiconductor devices, the conductivity types of the substrates 1 and 7 used are limited depending on the device structure.

Problems to be Solved by the Invention The purpose of the present invention is to solve the above-mentioned technical problems,
It is an object of the present invention to provide a method for manufacturing an optical semiconductor device, which enables the formation of a thin current confinement layer regardless of the conductivity type of the substrate.

Means for Solving the Problems The present invention provides a method for depositing a first non-doped film onto a GaAs substrate 21 of one conductivity type by metalorganic chemical vapor deposition.
GaAs layer 22, high resistance Ga _1-x AlxAs layer 23,
A second non-doped GaAs layer 24 is laminated in this order, and a V-groove 25 having a depth reaching from the surface of the second non-doped GaAs layer 24 to the one conductivity type GaAs substrate 21 is formed. A GaAlAs cladding layer 2 of one conductivity type is formed inside and on the second non-doped GaAs layer 24.
6, a GaAlAs active layer 27 of the other conductivity type, a GaAlAs cladding layer 28 of the other conductivity type, and a GaAs cap layer 29 of the other conductivity type are formed in this order by a liquid phase growth method. This is a method for manufacturing an optical semiconductor element.

Function According to the present invention, by increasing the resistance when forming the Ga _1-x AlxAs layer and using it as a current confinement layer, current confinement can be achieved regardless of the conductivity type of the substrate.

In particular, according to the present invention, the second non-doped GaAs layer 24 makes the high resistance Ga _1-x AlxAs layer 23 high in resistance to prevent it from becoming low resistance, and also
Even if there is an oxide layer on the Ga _1-x AlxAs layer 23, the GaAlAs cladding layer 26 of one conductivity type can be easily grown by liquid phase growth.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention. The semiconductor substrate 20 includes a non-doped GaAs layer 22 and a high resistance Ga _1-x AlxAs layer 23 on an N-type GaAs substrate 21.
and a non-doped GaAs layer 24 are stacked in this order by organometallic chemical vapor deposition. The non-doped GaAs layer 22 has a thickness of, for example, 0.3 μm.
The thickness of the Ga _1-x AlxAs layer 23 is selected to be 0.1 μm, and the thickness of the non-doped GaAs layer 24 is selected to be 0.3 μm.
Here, the non-doped GaAs layers 22 and 24 are provided to prevent the resistance of the Ga _1-x AlxAs layer 23 from decreasing due to dopant diffusion.

The conditions for increasing the resistance of the GaAlAs layer 23 by organometallic chemical vapor deposition are the substrate temperature during growth, group V (AsH ₃
The ratio of the partial pressure of the gas) to the partial pressure of the group (trimethylgallium and trimethylaluminum or trimethylgallium and trimethylaluminum), the so-called /ratio, and the geometry of the reactor. For example, it is known that increasing the aluminum composition or lowering the growth temperature increases the resistance.

As a method for increasing the resistance, the resistance can be increased by decreasing the carrier concentration. Also, by lowering the growth temperature or by selecting the partial pressure ratio of the gases,
Designs with even higher resistance values are possible. A method for achieving high resistance using organometallic chemical vapor deposition is disclosed in "Nikkei Electronics", January 17, 1983 issue, pages 189 to 212, and in particular,
It is clear from Figure 5 on page 195 and the related explanation, and this document also states that GaAlAs is
It has also been shown that resistance values an order of magnitude higher than GaAs are possible.

FIG. 2 is a cross-sectional view showing the structure of a semiconductor laser device 30 in which a channel is formed on the semiconductor substrate 20 of FIG. First, from the surface of the non-doped GaAs layer 24 of the semiconductor substrate 20,
A V-groove 25 having a depth of 100 mm is formed by, for example, a chemical etching method. After that, N is applied inside the V groove 25 and on the non-doped GaAs layer 24.
a P-type GaAlAs cladding layer 26, a P-type GaAlAs active layer 27, a P-type GaAlAs cladding layer 28, and a P-type GaAlAs cladding layer 26;
A GaAs cap layer 29 is laminated in this order by liquid phase growth. Note that when stacking layers using the liquid phase growth method, it is difficult to grow the Ga _1-x AlxAs layer 23 because there is an oxide layer on it.
Without the GaAs layer 24, it will not grow uniformly on the substrate. In this embodiment, the non-doped GaAs layer 24
2, uniform growth can be achieved on the substrate 20 as shown in FIG.

After obtaining the structure shown in FIG. 2 in this way, after forming electrodes, it was divided into individual elements and placed on an N-type GaAs substrate.
A semiconductor laser device 30 having a high resistance GaAlAs layer 23 serving as a current confinement layer on top of the semiconductor laser device 30 can be obtained.

Effects As described above, according to the present invention, high resistance
By using a Ga _1-x AlxAs layer as a current confinement layer, it becomes possible to constrict current regardless of the conductivity type of the substrate, and a semiconductor device with a relatively thin current confinement layer is realized. can do.

In particular, according to the present invention, one conductivity type (N-type in the above embodiment) is formed by metal-organic chemical vapor deposition.
A first non-doped GaAs layer 2 is formed on a GaAs substrate 21.
2, a high resistance Ga _1-x AlxAs layer 23, and a second non-doped GaAs layer 24 are stacked in this order,
In order to make the high resistance Ga _1-x AlxAs layer 23 high and prevent it from becoming low resistance, the second non-doped layer 23 described above is
A GaAs layer 24 is formed, and this second non-doped
The GaAs layer 24 also ensures that a GaAlAs cladding layer 26 of one conductivity type is formed by liquid phase epitaxy even in the presence of an oxide layer on the high resistance Ga _1-x AlxAs layer 23, 26, a GaAlAs active layer 2 of the other conductivity type (P type in the above embodiment)
7 and the other conductive type GaAlAs cladding layer 28
and the GaAs cap layer 29 of the other conductivity type can be formed in a liquid phase in this order.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the semiconductor substrate 20, FIG. 2 is a sectional view of the semiconductor laser element 30, and FIGS.
The figure is a cross-sectional view of a prior art semiconductor laser device. 20...Semiconductor substrate, 21...N-type GaAs substrate, 2
2...Non-doped GaAs layer, 23...High resistance GaAlAs
layer, 24...non-doped GaAs layer, 25...V groove, 3
0...Semiconductor laser element.

Claims (1)

[Claims] 1. One-sided conductivity type by metalorganic chemical vapor deposition method.
A first non-doped GaAs layer 2 is formed on a GaAs substrate 21.
2, a high resistance Ga1-xAlxAs layer 23, and a second non-doped GaAs layer 24 are laminated in this order, and the depth from the surface of the second non-doped GaAs layer 24 to the one conductivity type GaAs substrate 21 is determined. After that, a GaAlAs clad layer 2 of one conductivity type is formed in the V groove 25 and on the second non-doped GaAs layer 24.
6, a GaAlAs active layer 27 of the other conductivity type, a GaAlAs cladding layer 28 of the other conductivity type, and a GaAs cap layer 29 of the other conductivity type are formed in this order by a liquid phase growth method. A method for manufacturing semiconductor devices.