JPH0243788A - Multi-wavelength integrated semiconductor laser device and its manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a laser device whose active layers are uniform in the laser characteristic and which is long in a life span without imposing any restriction on the material and the composition of the active layers by a method wherein two or more kinds of active layers, which oscillate light rays different from each other, are laminated, and impurity is diffused to the place near the active layers. CONSTITUTION:Two or more kinds of active layers 41-43, which oscillate light rays whose wavelengths are different from each other, are laminated, and then impurity is diffused so as to reach to the active layers 41-43 or the position near them for the formation of carrier injection regions 103, 203 and 303 to enable the layers 41-43 to be driven independently from each other. For instance, an n-type GaAs buffer layer 6 and an n-type first clad layer 5 are formed on an n-type GaAs substrate 7, and n<->-type barrier layers 34, 33, 32 and 31 and the n<->-type or undoped active layers 43, 42 and 41 whose oscillating light rays are different from each other in wavelength, are alternately formed in succession thereon. Next, Be is injected in stripes to form the p<+> regions 303, 202 and 103 corresponding to the active layers 43, 42 and 41 respectively. Then, a high resistance second clad layer 2 and a high resistance cap layer 1 are formed, and Zn is diffused in stripes to form the p<+> regions 302, 202 and 102.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a multi-wavelength integrated semiconductor laser device that has a plurality of types of active layers that oscillate light of different wavelengths, and each active layer can be driven independently, and its Regarding the manufacturing method.

[Prior Art] Conventionally, multi-wavelength integrated semiconductor laser devices have been used, for example, in optical communications, and methods such as the following (1) and (2) are known as methods for manufacturing the same.

(1) A manufacturing method for forming active layers with different compositions at desired positions using ternary or higher compounds that can form layers with different compositions depending on the surface shape of the base layer (Japanese Patent Laid-Open No. 59-1654
Publication No. 87, etc.). FIG. 4 is a schematic cross-sectional view showing a laser device obtained by such a manufacturing method, in which active layers 60a having different compositions are placed at predetermined positions on a substrate 401,
60b is formed, and electrodes 70a and 70b for independently driving these active layers are formed.

(2) A manufacturing method in which a first film is formed, then a desired etching is performed to reach the active layer, and then a second film is formed (Japanese Unexamined Patent Publication No. 152183/1983, etc.). FIG. 5 is a schematic cross-sectional view showing a laser device obtained by such a manufacturing method, in which active single layers 80a, 80b, and 80c each having a ridge-like shape and having different oscillation wavelengths are formed at predetermined positions on a substrate 401. are formed, and each electrode 90a, 90b is used to independently drive the active layer.
90c is formed.

[Problems to be Solved by the Invention] In the above manufacturing method (1), only a compound that is dependent on the shape of the base can be used to form the active layer, there are restrictions on the material and composition of the active layer, and it is difficult to control the wavelength. There are limits. Furthermore, since the shape of the underlying layer differs depending on each active layer, the cross-sectional shape of each active layer also naturally changes, and therefore there is a drawback that laser characteristics such as astigmatism and threshold current differ depending on each active layer. .

In the above manufacturing method (2), since etching to reach the active layer is an essential step, the active layer may come into direct contact with the atmosphere or the etching solution, which may cause oxidation or processing damage to the active layer. The introduction of concomitant defects may occur and therefore the laser properties may differ from each active layer and the lifetime of the laser may be shortened.

The present invention has been made to solve these problems, and its purpose is to have no special restrictions on the material and composition of the active layer, to make the laser characteristics of each active layer uniform, and to shorten the laser life. It is an object of the present invention to provide a method for manufacturing a multi-wavelength integrated semiconductor laser that does not require the following steps.

[Means for Solving the Problems] The present invention includes (a) a process of laminating a plurality of types of active layers that oscillate light of different wavelengths, and (b) a position at or near a position reaching the plurality of types of active layers. A method for manufacturing a multi-wavelength integrated semiconductor laser device, comprising the step of forming a carrier injection region for independently driving the active layer by diffusing impurities up to It is an integrated semiconductor laser device.

In the method of the present invention, since the carrier injection region is formed by diffusion of impurities, each active layer can be independently driven in a planar state formed in a stacked manner with appropriate layers interposed therebetween, as shown in FIG. 2, for example. . Therefore, there is no need to partially change the composition of the active layer within the same layer as shown in FIG. 4, and there is no need to etch the active layer into a ridge shape as shown in FIG. Therefore, there are no special restrictions on the material and composition of the active layer, the laser characteristics of each active layer are uniform, and the life of the laser is less likely to deteriorate.

Hereinafter, the manufacturing method of the present invention will be explained in detail along the steps.

(a) First, multiple types of active layers that oscillate light of different wavelengths are formed in a stacked manner.

For example, by appropriately controlling the material, composition, layer thickness, etc. when forming the active layer, it is possible to form a plurality of types of active layers that emit light of different wavelengths. its materials, composition,
The layer thickness may be appropriately determined depending on the desired oscillation wavelength, and is not particularly limited in the present invention.

The plurality of active layers may be formed in a laminated manner with appropriate layers (barrier layers, etc.) interposed therebetween, as shown in FIG. 2, for example. In the present invention, the laminated active layer can be driven independently as it is, so that the problem caused by the etching of the active layer as shown in FIG. 5 described above does not occur.

Furthermore, in the present invention, since each active layer is formed in a laminated manner, there is no particular need to control the composition by the underlying shape as shown in FIG. There is no limit to the cross section of each active layer, and the cross section of each active layer can be made uniform.

(b) Next, by diffusing impurities to a position reaching or near the plurality of types of active layers, a carrier injection region for independently driving the active layers is formed.

The type of impurity is not particularly limited as long as it can form a region into which carriers can be injected into each active layer, and may be appropriately determined depending on the type of material constituting the diffused portion. For example, in the case of an AlGaAs-based semiconductor, Be%Zn, Ge, S, Si, etc. can be used.

The impurity is diffused by focused ion beam implantation by changing the acceleration voltage until it reaches the corresponding active layer or a position near it. The position in the vicinity may be any position that allows carriers to be well injected from the impurity diffusion region to the active layer. Further, the impurity diffusion is performed so that the diffusion regions for each active layer do not touch each other, that is, each active layer can be driven independently.

After forming a plurality of types of active layers and carrier injection regions as described above, a multi-wavelength integrated semiconductor laser device can be completed through desired steps.

The desired process is a process of forming a cladding layer, a cap layer, etc., and diffusing impurities into these layers again.

For example, as a preferred embodiment of the present invention, the following A
A method for manufacturing an lGaAs-based semiconductor laser can be mentioned.

(a) Forming a plurality of active layers and barrier layers on a suitable brainer substrate in a brainer-like surface.

(B) A carrier injection region (
Form a).

(c) A cladding layer, a cap layer, etc. are formed on the brainer-like surface after the carrier injection region (a) is formed.

(d) At the desired position of the cladding layer and cap layer, Z
A carrier injection region (b) is formed by diffusing n, etc. to a position reaching the carrier injection region (a).

(e) An independent electrode is formed at a position corresponding to the carrier injection region (b).

By the manufacturing method of the above aspects, good AlGaA
An s-based multi-wavelength integrated semiconductor laser device can be obtained.

Performing the impurity diffusion twice as described above is practical because it allows for well-controlled diffusion and simplifies the manufacturing process.

Further, in the above-described embodiment, the formation of the crat layer and the cap layer and the second diffusion of impurities can be performed on the Brenna-shaped surface, so that good crystal growth and impurity diffusion can be easily achieved. On the other hand, in the above-mentioned conventional method (2), since the surface after etching is uneven, problems such as abnormal growth of crystals and segregation of impurities may occur.

The multi-wavelength integrated semiconductor laser device obtained by the manufacturing method of the present invention as described above is useful in fields such as optical communications, for example.

Furthermore, as is clear from the above description of the manufacturing method, the configuration of the multi-wavelength integrated semiconductor laser device obtained by the manufacturing method of the present invention includes multiple types of active layers that oscillate light of different wavelengths and, if necessary, has a desired barrier layer and a carrier injection region for independently driving the active layer, and the carrier injection region diffuses impurities to a position reaching or near the plurality of active layers. This device is characterized in that it is formed by.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 First, as shown in FIG. 1, on an n-type GaAs substrate 7,
An n-type GaAs buffer layer 6 and an n-type first cladding layer 5 are formed, on which are formed an n-type barrier layer 34, 33, 32, 31, and an n-type or undoped active layer 43.33 having a different oscillation wavelength.
42 and 41 were formed sequentially and alternately.

Next, by focused ion beam implantation, the Be was implanted into a width of 2 p with acceleration voltages of 40 kV, 60 kV, and 80 kV, respectively.
Inject a dose of about 1X10'' in stripes of m,
p1 regions 303.203.corresponding to each active layer.
103 was formed.

Next, as shown in FIG. 2, the high resistance second clad N2
, a high resistance cap layer l was formed. Thereafter, a diffusion window was formed using the 5iJ4 film as a mask, and the Zn was sealed in a quartz ampoule at the same time as the ZnAs in the Be implanted region 303.2.
The heat is diffused in stripes with a width of 4 pm until reaching 03.103, and the corresponding p+ regions 302.202.
102 was formed. Next, an n-type common electrode 401 and p-type independent electrodes 301, 201, and 101 were formed, and a Fabry bellows resonator was formed between the folds.

In the multi-wavelength integrated semiconductor laser device manufactured as described above, when a forward voltage is applied between the electrode 101 and the electrode 401, electrons are injected from the first cladding layer 5 into the plurality of active layers 43, 42, 41. However, since the distance to the active layers 43, 42, 41 is sufficiently short compared to the electron diffusion length, electrons are injected into each active layer almost equally. On the other hand, holes flow from the Be injection region to the active layer 43, 42, 41 by the product M
However, since the diffusion length of the holes is short, most of the holes are injected into the active layer 41 closest to the Be injection region. Therefore, recombination of electrons and holes occurs within the active layer 41, and light (λ1) of a wavelength corresponding to the active layer 41 is generated. Similarly, electrode 201.401 and electrode 301.
By applying a forward voltage between 401 and 401, the active layer 4
From 2.43, the light of the corresponding wavelength (λ2, λ3
) occurs.

In this example, each layer was formed by the molecular beam epitaxy method (MBE method), and the thickness etc.
The procedure was as shown in Table-1.

Table 1 The wavelengths obtained with the above configuration are λ3=approximately 880 nm and λ=approximately 86 nm corresponding to the active layers 43, 42, and 41, respectively.
0 nm, and λ3=about 840 nm.

In this example, multiple wavelengths were obtained by changing the compositions of Ga and A1 in the active layer, but it is also possible to utilize differences in quantum levels due to differences in the thickness of the active layer.

In addition, in this example, the molecular beam epitaxy method (for layer formation) and the focused ion beam implantation method (for impurity diffusion) are used, so if the imaging equipment is connected, up to the second film formation. It is possible to carry out in a vacuum.

Example 2 After the Be diffusion step in Example 1, as shown in FIG. 3, a high resistance region is formed by implanting boron or gallium to a depth that divides all the active layers.
A multi-wavelength integrated semiconductor laser device was manufactured in the same manner as in Example 1 except that 502 was formed.

According to this embodiment, electrical isolation between individual lasers is improved, and in particular, it is possible to reduce crosstalk caused by electrical leakage.

[Effects of the Invention] As explained above, in the manufacturing method of the present invention, since the carrier injection region is formed by diffusion of impurities,
The active layer can be driven independently while remaining in a laminated state, so there are no special restrictions on the material and composition of the active layer, and the laser characteristics of each active layer are uniform, so that the laser life is not shortened. A multi-wavelength integrated semiconductor laser device can be obtained.

[Brief explanation of the drawing]

1 and 2 are schematic sectional views showing the process of the method of Example 1, FIG. 3 is a schematic sectional view showing the process of the method of Example 2, and FIGS. 4 and 5 are schematic sectional views showing the process of the method of Example 2. FIG. 2 is a schematic cross-sectional view illustrating a multi-wavelength integrated semiconductor laser device obtained by the method. l... High resistance cap layer 2... High resistance cladding layer 31-34... N-type barrier layer 41-43... Active layer 5... N-type cladding layer 6... P-type buffer layer 7.
...N-type substrate lol, 201.301...P-type independent electrode 102,
202.302... Zn diffusion region (carrier injection region) 103.203, 303 ・Be diffusion region carrier injection region) 401... n-type common electrode

Claims (1)

[Claims] 1) (a) A process of laminating multiple types of active layers that oscillate light of different wavelengths, and (b) Diffusing impurities to a position reaching or near the multiple types of active layers. A method for manufacturing a multi-wavelength integrated semiconductor laser device, comprising the step of forming a carrier injection region for independently driving the active layer. 2) A multi-wavelength integrated semiconductor laser device manufactured by the manufacturing method according to claim 1.