JPS61191089A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To modulate each laser independently, in a monolithic, multiple-wave, semiconductor laser, by electrically isolating the same multiplex quantum-well layer, changing the shapes of the well layers locally, thereby emitting a plurality of desired different wavelengths of emitted light simply. CONSTITUTION:On an n<+>GaAs substrate 6, an nGaAs layer 7 as a buffer layer, an nGa1-yAlyAs layer as a clad layer 8, an MQW layer 9 as an active layer, a pGa1-yAlyAs layer as a clad layer 10, and a p<+>GaAs layer 11 as a cap layer are sequentially grown. After the epitaxial growth, a laser beam 14 and a laser beam 15 are locally projected. Thus the temperature is increased close to 1,000 deg.C. The annealing degrees in a region C and a region D are different. Then, protons 16 are implanted to the boundary between the region C and the region D from the surface. The proton-implanted region becomes an electrically isolating region 17. The active layer of each semiconductor laser is electrically independent and can be independently modulated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multi-wavelength semiconductor laser having a plurality of different oscillation wavelengths and a method for manufacturing the same.

2. Description of the Related Art Recently, in the field of optical information processing, semiconductor lasers for writing, reading, and erasing data are used in optical recording and reproducing devices such as optical disks. Depending on the application, there may be cases where it is desired to read immediately after writing, or cases where it is desired to write and read after erasing. In this case, the wavelength of the semiconductor laser light for writing (assumed to be λ1)
It is better that the readout wavelength (λ) is different from the wavelength (λ1>λR). This is because these semiconductor lasers are placed close to each other, so to avoid mixing the writing signals during reading, and to make the reading signals accurate, the spot diameter of the reading laser beam must be adjusted. This is also to make it smaller (shorten the wavelength).

In addition, when recording high-definition television images, there is also a desire to write luminance signals and color signals using separate laser wavelengths. Considering these considerations, there is an increasingly strong desire to integrate a plurality of semiconductor lasers with different wavelengths into a single chip. There is also a strong demand for it as a light source for optical multiplex communications for large-capacity communications.

Conventionally, in this type of semiconductor laser, normal double heterostructures as shown in FIG. 5 are stacked twice, and a part of the upper double heterostructure is removed to create a semiconductor laser for the lower double heterostructure. Some have electrodes formed for them (
5hiro 5ak2Li :KleOtrOniC8
L8tt, 18 (19B 2) 17. ).

Here, the active layer 1 is connected to the electrode 2. Opposite to active m3 The electrodes 4 each serve as an electrode for driving a laser.

Electrode 5 is a common electrode, and now when the semiconductor laser in the region B is driven, a laser beam with an oscillation wavelength λ is emitted, and when the semiconductor laser in the B region is driven, a laser beam with an oscillation wavelength λ2 is emitted. It had become.

Problems to be Solved by the Invention In FIG. 5, the electrode material in area A (for example, Au/Zn
) and the electrode material of region B (e.g. U/Sn), so at least three electrode formation steps are required;
Another problem is that the process becomes complicated, such as the active region of the high-performance conductor laser being composed of different epitaxial layers. Furthermore, when considering the area between electrodes 4 and 5 as one semiconductor laser, the sheet resistance in the area below electrode 6 increases, so the threshold current for oscillation increases compared to the semiconductor laser between electrodes 2 and 5. There were 6 problems with poor characteristics.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention forms the active layer of a multi-wavelength biolayer conductor laser by electrically separating the same N region, and also obtains different oscillation wavelengths. It is something. That is, in order to solve the above-mentioned problems, the present invention alternately deposits a first semiconductor layer and two or more types of compound semiconductor thin films having different compositions, such as binary, ternary or more, on a compound semiconductor substrate. It has a laminated structure in which a second semiconductor layer and a third semiconductor layer are sequentially formed in a multi-layered thin film structure, and the thickness of the thin film in the second semiconductor layer or the shape of each thin film boundary region The present invention provides a multi-wavelength semiconductor laser in which a plurality of regions having different wavelengths are electrically separated. In order to change the oscillation wavelength, for example, the same growth layer region may be separated and laser annealed.
administer.

Function The present invention provides the above structure in which the active layer of the semiconductor laser is a multiple quantum well layer (touati-quantum well layer).
11 layer S MQW layer) or single quantum well layer (Sin
It is formed of a gla-quantum well 1 layer (SQW layer). This MQWil is composed of a thin film multilayer structure in which well layers and barrier layers are alternately repeated with a thickness of about 20A to 200A. Generally, the emission wavelength in this MQWI is determined by the shape and thickness of the layer, so the shape and thickness of the well layer of each electrically isolated MQW layer are determined by the shape and thickness of the MQW layer during epitaxial growth. can be changed by performing local annealing using laser annealing, etc., and thereby the wavelength of the laser light emitted from each MQWil can be changed.

EXAMPLE The present invention will be explained in detail using FIGS. 1 to 4. FIG. 1 shows the laminated structure of the device of this embodiment formed by epitaxial growth.

Now, explanation will be given by taking GaAs-based semiconductor material as an example. First, an n"GaAs layer 7 as a buffer layer and an nG layer as a cladding layer 8 are formed on an n" GaM S substrate.
a, -yMJyAs, MQWIs as active layer
, pGa as cladding layer 10, -Amly As
, and a p+G11L S layer 11 as a cap layer is grown.

Note that electrodes as a semiconductor laser are omitted.

FIG. 2 is an enlarged view of the MQW layer 9 in FIG.

The MQW layer 9 has a barrier layer of, for example, Ga, -Al, an S layer (12Cx<y)sz, and a u layer of, for example, Ga.
The As layer 13 is constituted by alternately repeating thin films of about 20 to 200 layers.

FIG. 3 shows the cross-sectional structure of this embodiment. However, the electrodes are omitted. First, after epitaxial growth as shown in FIG. 1, laser beams 14 and 15 are locally irradiated. For example, a YAG laser with an output of 6 W is used as the laser. The spot diameter can be narrowed down to about 6 μm, and the spot diameter can be reduced to about 6 μm.
By changing the speed, laser beams 14 and 16
The laser beam intensity of can be varied. Now, the distance from the surface to the MQW layer 9 as the active layer is 1 μm to 2 μm.
Therefore, it is possible to sufficiently raise the temperature to nearly 1000° C. with this strength. By doing this, the way the laser annealing is performed in the region C and the region P is different. Next, when protons 16 are irradiated from the surface at, for example, 300 KeV at the boundary between the region C and the region C, it is possible to implant the protons 16 to a depth of approximately 2 μm, and this proton irradiation region becomes an electrically isolated region 17.

By the way, as shown in FIG. 4, the laser annealed MQWN9 has a sharp conduction band structure after crystal growth on the left side (2L) of FIG. The boundary between the barrier layer 12 becomes gentle. This is because the constituent elements were worked up by the energy of the laser annealing μ. This shape can be changed by changing the intensity of laser annealing. Figure 4 shows the quantum level of electrons, and as the shape collapses, the quantum level tends to rise. Therefore, by changing the amount of laser annealing, λ can be reduced from region C.

An emission wavelength of λ4 can be emitted from the region. The difference in emission wavelength Δλ is several nm
You can get enough. Now, as a multi-wavelength laser, when three or more types of emission wavelengths are desired, we have described two areas as representatives, but if two wavelengths are sufficient, in Figure 3, for example, laser annealing is applied to only one area. , it goes without saying that the other structure may be used as it is after crystal growth. Electrical separation of regions C and D may be performed after the laser annealing process or may be performed before the laser annealing process. As a separation method, in addition to the above-mentioned proton irradiation, the region corresponding to the separation region 17 may be removed by etching, or after removal by etching,
A Si3N4 film, a Sin film, a polyimide film, or the like may be buried. The MQW layer 9 is preferably formed by metal organic chemical vapor deposition (MoCVD) or molecular beam epitaxy (MBK). The active layers of each semiconductor laser are electrically independent, and can be independently modulated by providing independent drive electrodes.

Effects of the Invention According to the semiconductor device of the present invention, in the structure of a monolithic multi-wavelength semiconductor laser, identical multiple quantum well layers can be electrically separated and the shape of the well layer can be locally changed by, for example, laser annealing. As a result, it is possible to provide a semiconductor laser which can easily emit a plurality of desired different emission wavelengths and which can independently modulate each semiconductor laser. 1.
If the present invention is applied to a long wavelength laser in the 3 μm band, it can also be applied to optical multiplex communication. In the field of optical information processing, there is a demand for optical recording and reproducing devices capable of high-density, high-speed transfer, and semiconductor lasers are desired to have shorter wavelengths. Not limited to GaAs systems, I n , -x GaxAs y p+ -y/I
Up system.

I n 1- X GaxAs, p + -y/ I
n1-zGaxp/GaAs system.

(A4xGa j −z )y In j −y p
/Gahs system, etc., and will greatly contribute to the practical application of monolithic multi-wavelength lasers.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining an epitaxial growth substrate of an embodiment of a semiconductor device of the present invention, FIG. 2 is an enlarged view of the main part of the semiconductor device, and FIG. 3 is a semiconductor laser of an embodiment of the present invention. FIG. 4 is a diagram for explaining the shape change of the conduction band due to local annealing μ, and FIG. 5 is a diagram for explaining the conventional semiconductor laser. 6...n"Gamus board, 7...HG
a As layer, 8゜1o... cladding layer, 9...
...MQW active layer, 12 ... Barrier layer, 1
3... Well layer, 14, 15... Laser beam, 16... Proton. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (10)

[Claims] (1) A second thin film multilayer formed by alternately stacking a first semiconductor layer and three or more layers of two or more types of compound semiconductor thin films having different compositions, such as binary or ternary or more, on a compound semiconductor substrate. The semiconductor layer has a laminated structure in which a semiconductor layer of A semiconductor device characterized by: (2) The forbidden band width of the first and third semiconductor layers is equal to or wider than the widest forbidden band of the semiconductor of the second semiconductor layer of the thin film multilayer.
The semiconductor device according to item 1). (3) The semiconductor device according to claim (1), wherein the semiconductor device is a multi-wavelength semiconductor laser with different oscillation wavelengths. (4) The compound semiconductor substrate is GaAs, and the semiconductors in other regions are GaAs and Ga_1_-_xAl_xAs(0
≦x≦1).
The semiconductor device according to item 1). (5) A second thin film multilayer formed by alternately stacking the first semiconductor layer and three or more compound semiconductor thin films of two or more types with different compositions of two or three or more elements on a compound semiconductor substrate. A region having a laminated structure in which a semiconductor layer and a third semiconductor layer are sequentially formed, and reaching from the first semiconductor layer side to at least the third semiconductor layer side end of the second semiconductor layer of the thin film multilayer. Locally annealing is performed on a part or the entirety of the compound semiconductor substrate until the amount of local annealing is applied to at least two regions on the compound semiconductor substrate, and each of the local annealing regions is electrically isolated. A method for manufacturing a featured semiconductor device. (6) The method for manufacturing a semiconductor device according to claim (5), wherein the local annealing is performed by laser annealing. (7) The method for manufacturing a semiconductor device according to claim (6), wherein the amount of local annealing is controlled by the power and irradiation amount of the laser. (8) The method for manufacturing a semiconductor device according to claim (5), wherein the electrical isolation is performed after local annealing treatment. (9) A patent claim characterized in that the electrical isolation is performed by proton irradiation, removal by etching of the semiconductor layer corresponding to the electrical isolation region, or by filling the etched removal region with silicon nitride, silicon oxide, or polyimide. A method for manufacturing a semiconductor device according to item (5). (10) The method for manufacturing a semiconductor device according to claim (5), wherein the thin film multilayer region is formed by metal organic vapor phase epitaxy.