JPS63197394A - Semiconductor laser array element - Google Patents

Abstract

PURPOSE:To prevent the damage of a laser reflection surface, and increase the data transfer speed, by arranging, between oscillation parts, a region whose resistance is made high by radiating high energy particles, and separating them electrically. CONSTITUTION:On an n-type substrate 1, the following are crystal-grown; an n-type AlxGa1-xAs clad layer 2, an AlyGa1-yAs active layer 3, a p-type AlzGa1-zAs block layer 4, and an n-type GaAs block layer 5. Then the layer 5 is subjected to a selective etching so as to reach the layer 4, and filled with the layer 4. In the active layer wherein the layer 5 is subjected to a selective etching, a current is constricted and injected. A part of mode vertically distributed from the active layer 3 reaches the block layer 5 in both end-regions, and suffers loss. Thus a laser oscillation part is constituted. The upper surface of the laser oscillation part is coated with Au, and irradiated selectively by proton beam. Thereby, a high resistance regions 6 deeper than the layer 3 is formed between the laser oscillation parts. Next, p-side electrodes 7 are formed separately in each oscillation part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser array element including a plurality of independently drivable laser oscillation sections.

[Conventional technology]

Semiconductor laser arrays equipped with a plurality of independently driven laser oscillation units have a wide range of uses as light sources for information processing equipment such as optical disk devices and laser printers, and exhibit particularly excellent characteristics as light sources for optical disk devices.

When a single semiconductor laser is used as a light source, the laser beam becomes 1
, information must be recorded, reproduced, and erased independently, and it takes time to drive the information. However, when a semiconductor laser array is used, multiple laser beams are focused on the same track on an optical disk. Recording/playback (error detection)/
Erasing can be shared and these operations can be processed continuously and simultaneously. In addition, recording and playback can be performed in parallel by focusing multiple laser beams on multiple tracks, and the information transfer speed can be increased by several times the number of beams compared to a single beam. There are advantages.

Semiconductor laser arrays used in these applications must include a plurality of laser oscillation units and a structure for independently driving them. Conventionally, a common method has been to form a groove between the laser oscillation sections at least deeper than the active layer to electrically separate the laser oscillation sections from each other.

Figure 3 is from the magazine “Applied Physics Letters” (A
pplied Physics Letters)J
FIG. 4 is a cross-sectional view showing the structure of a semiconductor laser array described in Vol. 41, pp. 1040 to 1042, published in 1982.

AI containing an active layer 3 on a GaAs substrate 1! After crystal-growing the GaAs multilayer films 2 to 4 and 10 to 12 to simultaneously form multiple laser oscillation sections, a separation groove 14 deeper than the active layer (reaching the GaAs substrate 1) is formed by etching to form the oscillation section. electrical isolation between the two.

[Problem that the invention seeks to solve]

In this conventional method, the isolation groove 14 formed between the oscillating parts for electrical isolation has a depth of 4 to 5 μm or more and a width of 1 μm.
It was large, 0 to 20 μm or more. For this reason, there was a problem that the grooves 14 were an obstacle and the cleavage did not proceed smoothly, making it difficult to obtain a flat laser reflecting surface. Furthermore, due to the width of the groove and the necessity of the process for forming the groove, there is a limit to the spacing between the laser oscillation parts, which has conventionally been 100 μm or more. Multiple laser beams emitted from a semiconductor laser array are routed through the same lens onto an optical disk due to the simple structure of the device, easy alignment of positions, and high stability against external disturbances. However, the effective field of view of the collimating lens used for this is generally as narrow as 200 to 300 μm.

For this reason, conventional semiconductor laser arrays with wide spacing between oscillation units can only be used as light sources with a small number of beams, 2 to 3, which has been an obstacle to increasing the transfer speed of optical disk devices.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a semiconductor laser array element that eliminates damage to the laser reflecting surface and increases data transfer speed.

[Means for solving problems]

The structure of the present invention is a semiconductor laser array element in which a semiconductor multilayer film including an active layer is crystal-grown on a semiconductor substrate, and the semiconductor multilayer film has a plurality of oscillation parts each having a current confinement structure and an optical waveguide structure. , each of the oscillation sections is electrically isolated from each other by a high resistance region made high in resistance by irradiating high energy particles onto the semiconductor multilayer film, so that each of the oscillation sections can be driven independently of each other. It is characterized by what it did.

[Effect]

According to the configuration of the present invention, electrical isolation is achieved by providing regions between the oscillation parts that have a high resistance due to irradiation with high-energy particles, instead of the grooves in conventional semiconductor laser array elements. As a result, the spacing between the oscillating parts can be significantly narrowed compared to conventional methods, and a nearly flat element surface can be obtained, allowing cleavage to proceed smoothly due to the grooves.It is easy to cause damage to the laser reflecting surface. It can solve conventional problems such as

〔Example〕

FIG. 1 shows a perspective view of a semiconductor laser array element according to a first embodiment of the present invention. On the n-type GaAs substrate 1, the n-type A
(!, G a As cladding layer 2゜A j7y G
a 1-y As active layer 3. p-type Aff, Ga1-
2As block layer 4. After crystal growth of the n-type GaAs block layer 7, the n-type GaAs block layer 7 is grown by p-type Aff, Ga
1□Selective etching is performed on the stripes to a depth that reaches the As cladding layer 4, and further p-type Aez cladding is etched.
l-, filled with As cladding layer 4. In the active layer region where the n-type GaAs block layer 7 is selectively etched,
The current is constricted and injected, and a part of the mode distributed in the vertical direction from the active N3 reaches the block layer 7 at both end regions to obtain a loss, thereby forming a laser oscillation section.

The upper surface of this laser oscillation part is covered with an Au thin film and protons are selectively irradiated to form a high resistance region 6 at least deeper than the active layer 3 between the laser oscillation parts. Thereafter, p-side electrodes 7 were formed separately for each oscillation section.

In the semiconductor laser array thus formed, a plurality of laser oscillation sections are electrically separated by a high resistance region 6 formed by proton irradiation and can be driven independently. These high resistance regions 6 can be formed to have a width of 10 μm or less, making it possible to realize a semiconductor laser array element in which the interval between oscillation parts is 50 μm or less. Furthermore, since the grooves found in conventional elements are not required and a substantially flat element surface is obtained, cleavage proceeds smoothly and there is no damage to the laser reflecting surface.

FIG. 2 shows a perspective view of a semiconductor laser array element according to a second embodiment of the present invention. An n-type Al! x G a
l-x As cladding layer 2. n-type Al! .

Gal u As guide layer 10. klyGap,y
As active layer 3. p-type A ez Ga 1-2 A
The s-cladding layer 4 and the n-type GaAs block layer 5 were epitaxially grown using a liquid phase growth method.

Here, A! of the p-type and n-type cladding layers! ! The composition ratios x and z of the layers are larger than the Aff composition ratio y of the active layer, and the Ae composition ratio U of the guide layer is between the two. The active layer region of the groove portion forms an oscillation portion having a so-called PCW structure (plano-convex thin waveguide structure) in which the thickness of the adjacent guide layer is thin at the center of the groove portion. It is formed at a position corresponding to the groove with a depth that penetrates the n-type GaAs block M5. Zn, which is a p-type impurity, is selectively diffused in a stripe pattern to a depth penetrating the n-type GaAs block layer 5 at a position corresponding to the groove portion, thereby forming a current confinement structure.

As in the first embodiment, a high resistance region 6 is formed at least deeper than the active layer 3 between the laser oscillation parts by selectively irradiating protons, and the p-side electrode 7 is formed separately for each oscillation part. We fabricated a semiconductor laser array device equipped with multiple laser oscillation units that can be driven independently by the following methods.

In these first and second embodiments, a semiconductor laser array element having three oscillation parts is shown, but two or three oscillation parts may be used.
The present invention can also be applied to a semiconductor laser array element having a plurality of oscillation sections, and the structure of the oscillation section is not limited to these embodiments, and may be applied to other optical waveguide structures or current confinement structures. The present invention can also be applied to a semiconductor laser array element equipped with a semiconductor laser array element, and similar effects can be obtained.

The present invention can be applied to semiconductor laser array elements made of other semiconductor materials such as AJGa I nP and InGaAsP, and similar effects can be obtained.

〔Effect of the invention〕

According to the present invention, compared to conventional semiconductor laser arrays, it is possible to obtain a semiconductor laser array that does not require grooves for electrical isolation between oscillating parts and has a flat crystal surface, which reduces yield when forming reflective surfaces. can be improved.

Furthermore, it is possible to fabricate a semiconductor laser array with narrow spacing between oscillating parts, and it is possible to provide a light source suitable for increasing the data transfer rate using the parallel recording/reproducing method.

[Brief Description of the Drawings] FIGS. 1 and 2 are structural diagrams of semiconductor laser array devices according to first and second embodiments of the present invention, and FIG. 3 is a structural cross-section of an example of a conventional semiconductor laser array device. It is a diagram. 1--- n-type Ga As substrate, 2 q n-type A
I! )l Gal-gAs cladding layer, 3...
AI! yGa1-yAs active layer, 4-P type Al z
Ga 1-z As cladding layer, 5...n-type Ga
As block layer, 6... High resistance region, 7... P-side electrode, 8... N-side electrode, 9... P-type impurity diffusion region,
10-n-type Alu Ga1-, As guide layer, 11 ・
n-type AeuGa1-uAs cladding layer,
12...p-type GaAs cap layer, 13...
Insulating film, 14... isolation groove.

Claims (1)

[Claims] A semiconductor multilayer film including an active layer is crystal-grown on a semiconductor substrate, and each of the oscillation parts has a plurality of oscillation parts each having a current confinement structure and an optical waveguide structure in the semiconductor multilayer film. The semiconductor multilayer film is electrically isolated from each other by a high resistance region made high in resistance by irradiating high energy particles onto the semiconductor multilayer film, and each of these oscillation parts can be driven independently of each other. Semiconductor laser array element.