JPS6080291A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To enable the measurement of characteristics of the titled device in the wafer state by making each chip independent by a method wherein a lattice- form insulation region surrounding the ohmic contact layer of each chip is provided from the surface of an N-cap layer to an N-cap layer. CONSTITUTION:An N type clad layer 2 of GaAlAs, an N type active layer 3, and a P type clad layer 4 are superposed on an N type GaAs substrate 1, and an SiO2 mask having a stripe aperture of a required width is applied on the N- cap layer 5, and a stripe ohmic contact layer 6 of a required width reaching part of a layer 4 is formed by Zn diffusion. Next, an SiO2 mask covering a fixed area including the layer 6 is applied, and an insulation layer 7 is formed by proton irradiation reaching the layer 2. When the mask is removed, and Au series electrodes 8 and 9 are attached to the layer 5 and the substrate, a wafer provided with laser chips independent of each other in adjacency, and the interface of the layer 7 serves as an effective resonator plane. The adjacent chips can be photoelectrically measured in laser characteristics as a laser diode and a photo diode, and accordingly the titled device of high quality can be obtained.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a semiconductor laser device.

[Background of the invention]

Semiconductor laser devices having a double heterojunction can reduce the oscillation threshold current, and are being used particularly as light sources for fiber communications or compact disk printers. Conventionally, this type of semiconductor laser device has generally been manufactured using a liquid phase epitaxial growth method in the following manner.

That is, after an n-type LAD layer, an n-type or p-type active layer, a p-type LAD layer, and an n-type camp layer are successively provided on an n-type semiconductor substrate by, for example, liquid phase epitaxial growth, a predetermined width is formed. an ohmic contact layer having a stripe shape and penetrating the n-type cap layer and the p-type rad layer, and forming an electrode on the entire surface of the n-type cap layer including the ohmic contact layer and the 11-type semiconductor substrate; The company was manufacturing wafers for semiconductor laser devices. The electrical and optical characteristics of the semiconductor laser device made through the above process have the drawback that it is impossible to measure them unless the wafer for the semiconductor laser device is cleaved to a predetermined resonance length and made into chips. Ta.

In order to improve these drawbacks, the following measures have been taken. In other words, by determining the relationship between the photoluminescence intensity and the electrical characteristic values of the epitaxial wafer in advance, it is possible to easily inspect the quality of the epitaxial wafer.

(Japanese Unexamined Patent Publication No. 5'7-194542), or by applying a high current to the semiconductor laser device for a predetermined period of time to deteriorate the defective element, and then measuring the laser oscillation threshold current, the semiconductor laser device can be repaired in a short time. Means for determining quality (for example, JP-A-57-13'2568, JP-A-58-
21386). Among these methods, although the former method allows characteristics to be evaluated in the wafer state and the results can be fed back to the process at an early stage, it has the disadvantage that it cannot be evaluated if there is a layer that does not transmit photoluminescence on the surface of the wafer. In addition, while the latter method can reliably determine the quality of the semiconductor laser device, it requires cleavage and assembly processes as well as a large number of energizing equipment, and has the disadvantage that it is difficult to feed back the determination results to earlier processes. . Despite the above-mentioned circumstances, there has been a strong desire to determine the quality of manufactured semiconductor laser wafers at an early stage and, based on the results, to improve the quality of epitaxial wafers.0 [Object of the Invention] The present invention It is an object of the present invention to obtain a semiconductor laser device that can measure the electrical and optical characteristics of the semiconductor laser device in a wafer state, has high quality and high reliability, and is easy to manufacture.

[Summary of the invention]

In order to achieve the above object, a semiconductor laser device according to the present invention includes an n-type rad layer, an n-type or p-type active layer, a p-type cladding layer, and an n-type cap layer, which are sequentially formed on an n-type semiconductor substrate. and a stripe-shaped ohmic contact layer having a predetermined width at a depth that penetrates the n-type cap layer and reaches the p-type cladding layer. The sides of the n-type cladding layer, the n-type or p-type active layer at a depth reaching the n-type cladding layer are surrounded by an insulating region, and the surface of the n-type cap layer including the ohmic contact layer is covered with the insulating region. By providing the contact electrode and the electrode covering the back surface of the n-type semiconductor substrate, in a wafer state in which multiple chips of this semiconductor laser device are arranged adjacent to each other, a lattice-shaped insulating region surrounding each ohmic contact layer is formed. It is provided from the surface of the n-type cap layer to a depth reaching the n-type rad layer, so that each semiconductor laser chip is formed independently within the wafer.

[Embodiments of the invention]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing a wafer in which an ohmic contact layer is formed on a multilayer film on an n-type semiconductor substrate in the manufacturing process of an embodiment of a semiconductor laser device according to the present invention, and FIG.
1. A cross-sectional view showing the step of forming a grid-shaped insulating region on the wafer, FIG. 6 a cross-sectional view showing the step of forming electrodes on the wafer, and FIG. 4 a cross-sectional view of a semiconductor laser device obtained from the wafer. I'll go. In FIG. 1, an n-type GaAtAs cladding layer 2 is formed on an n-type GaAs substrate 1 using a well-known liquid phase epitaxial growth method, and an n-type or p-type Ga
A LAs active layer 3 and p-type GaA7As cladding layer 4
and an n-type 0aAs cap layer 5 are sequentially and continuously laminated. Next above! 5i on top of the 1 type 0aAs cap layer 5
02 membrane or At20. A first mask having stripe-like openings with a predetermined width is formed using a film or the like, and atoms such as Zn or Si are spread in areas other than the areas covered by this mask using a normal thermal diffusion method. Forgiveness, n-type 0aA
s cap layer 5f: through p-type 0aA7As cladding layer 4
A striped ohmic contact layer 6 having a predetermined width (several μ+n) is formed to a depth that reaches a part of the . After removing the first mask, a second mask covering a predetermined area including the ohmic contact layer 6 is applied again to the 5102 film or the At203 film on the n-type OaAs character 1M5, leaving a grid-like region. As shown in FIG. 2, an n-type G
The well-known protons penetrate through the aAs cap layer 5, the p-type GaAtA3 cladding layer 4, and the n-type or p-type GaAtAs active layer 6 to a depth that reaches a part of the n-type GaAtAs cladding layer 2. Insulating region 7 is formed using an irradiation method. After removing the second mask, the surface of the n-type OaAs camp layer 5, which includes the ohmic contact layer 6 and has a larger area than the second mask, and the n-type GaA
As shown in FIG.
When the system electrodes 8 and 9 are formed, a wafer for a semiconductor laser device is obtained in which a plurality of mutually independent semiconductor laser chips are formed adjacent to each other with side surfaces surrounded by insulating regions.

Furthermore, the semiconductor laser device obtained from the above wafer was
As shown in the figure, from the surface of the n-type GaAs cap layer 5 to the p-type GaAs cladding layer 4, the n-type or p-type
The side surface is recessed along the GaAtAs active layer 3 with an insulating region 7 having a depth that reaches a part of the n-type QaAtAs cladding layer 2, and the interface of the insulating region 7 serves as an effective resonator surface.

〔Effect of the invention〕

As described above, the semiconductor laser and the device according to the present invention penetrate the n-type rad layer, the n-type or p-type active layer, the p-type cladding layer, and the 01 layer, which are sequentially formed on the n-type semiconductor substrate, and pass through the p-type cladding layer. In a semiconductor laser device equipped with a striped ohmic contact layer having a predetermined width and a depth reaching 1, from the surface of the n-type cap layer to the p-type clad layer, 1.
The side surface of the n-type rad layer along the 1-type or p-type active layer is surrounded by an insulating region, and the electrode extends to the insulating region by covering the surface of the n-type cap layer including the ohmic contact layer. By providing an electrode covering the back surface of the n-type semiconductor substrate, in a wafer state in which a plurality of chips of the present semiconductor laser device are arranged adjacent to each other, the lattice-shaped insulating region surrounding each ohmic contact layer becomes an n-type semiconductor substrate. , from the surface of the top layer to a depth reaching the n-shaped rad layer, and each semiconductor laser chip independently forms a semiconductor laser device with the interface of the insulating region as the effective resonator surface. By making a pair of semiconductor laser chips function as a laser diode and a photodiode, laser characteristics can be measured electro-optically in the wafer state. Further, since the measurement results in the wafer state can be immediately fed back to the epitaxial growth process, it is possible to obtain a semiconductor laser device of high quality, high reliability, and easy to manufacture. Note that even if the formation of the lattice-shaped insulating regions in the wafer state is replaced with the formation of lattice-shaped grooves by chemical etching, the same effect as described above can be expected.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a wafer in which an ohmic contact layer is formed on a multilayer film on an n-type semiconductor substrate in the manufacturing process of an embodiment of a semiconductor laser device according to the present invention, and FIG. FIG. 6 is a cross-sectional view showing the step of forming an insulating region, FIG. 6 is a cross-sectional view showing the step of forming electrodes on the wafer, and FIG. 4 is a cross-sectional view of a semiconductor laser device according to the present invention. 1... N-type semiconductor substrate 2... N-type rad layer 6.
... N-type or p-type active layer 4... P-type rat layer 5... N-type cap layer 6゛°° ohmic contact layer 7... Insulating region 8.9...
Electrode attorney Junnosuke Donakamura

Claims (1)

[Claims] n-type rad layers formed sequentially on an n-type semiconductor substrate, n
or a multilayer film consisting of a p-type active layer, a p-type rad layer, and an n-type cap layer, and a stripe-shaped ohmic contact having a predetermined width at a depth that penetrates the n-type cap layer and reaches the p-type rad layer. In a semiconductor laser device comprising a layer, a side surface at a depth extending from the surface of the n-type cap layer to the n-type rad layer along the p-type, cladding layer, n-type or p-type active layer is surrounded by an insulating region; A semiconductor laser device comprising an electrode covering the surface of an n-type cap layer including an ohmic contact layer and reaching the insulating region, and an electrode covering the back surface of the n-type semiconductor substrate.