JPS62268188A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain excellent luminous characteristics by implanting an impurity forming a conductivity type reverse to the conductivity type of semiconductors to the semiconductors laminated in the same conductivity type including active layers and shaping striped P-N junctions in each semiconductor laser. CONSTITUTION:An N-Al0.3Ga0.7As clad layer 102, an N-GaAs layer 103, clad- layer N-Al0.3Ga0.7As 104 and cap-layer N-GaAs 105 are formed onto the high resistance GaAs of a substrate 101. A diffusion mask is formed by using Si3N4, Zn is diffused, and diffusion sections 112, 113 are shaped through double diffusion. The regions 112, 113 function as P-type regions, and are employed as active layers, currents transversely flow through the layer 103, and light is emitted from a section 111. Respective electrodes 108, 107 are formed, and Au-Cr is used as the P type 108 and Au-Ge-Ni/Au as the N type 107. Accordingly, luminous efficiency is improved, and homogeneous output can be extracted with excellent reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a semiconductor laser device in which a plurality of semiconductor lasers are monolithically formed.

[Prior art]

Conventionally, when designing an optical scanning device using a plurality of semiconductor lasers or light emitting diodes (LEDs), as disclosed in Japanese Patent Application Laid-Open No. 59-126, light is emitted from a light emitter as shown in FIG. The emission direction is one point P. The light sources are arranged so that they intersect at the same point, and the scanning spot (not shown) can be scanned with a plurality of scanning spots while maintaining a good image formation state.

FIG. 3 shows a typical conventional example, and is a diagram of the optical system between the light source and the deflector, viewed from a direction perpendicular to the deflection scanning plane. 31a and 31b are semiconductor lasers, and each laser is arranged on the mount 32 so that its light beam generating surface is parallel to the end surface of the mount 32. Mount 32 provided with semiconductor lasers 31a and 31b
The end faces 32a, 32b of each laser 31a, 31b
A point P where the central rays ha and hb of the divergent luminous flux from are the same. It is set as if it had passed through.

In other words, if normal lines are drawn to the end faces 32a and 32b at the positions where the semiconductor lasers (31a, 31b) are provided, each normal line is P. The end face 32a
and 32b are set. Furthermore, when viewed from a direction parallel to the deflection scanning plane, the central ray ha of each semiconductor laser,
P of hb. The position of the semiconductor laser provided on the marant 32 is set so that the position passing through the point is slightly displaced in a direction perpendicular to the deflection scanning plane. Above P. The point P in a predetermined vicinity of the deflection reflection surface 33 of the deflector is maintained in an optically conjugate relationship by the imaging lens 34.

In this way, in order to arrange multiple semiconductor light emitting devices (for example, semiconductor lasers) so that their respective light emission directions are different, they must be aligned on the mount and configured into a hybrid structure, as shown in the example above. I needed to. For convenience, the term "array laser" will be used below to refer to a plurality of semiconductor light emitting elements, but in principle it also applies to light emitters such as LED arrays.

Furthermore, when using a monolithically formed array laser, it is necessary to install some kind of optical system in front of the array laser. In an example disclosed in Japanese Patent Laid-Open No. 58-211735, a prism is placed in front of an array laser. This is shown in FIG.

FIG. 4 shows a cross section of a prism when a semiconductor array laser has five light emitting parts. 41 is five light emitting parts (41a, 41b, 41c, 41d, 41
42 is a prism. The central ray ha of the luminous flux from the light emitting part 41a is refracted by the inclined surface 42a, and the central ray ha of the luminous flux is refracted as if by P. It is bent as if it had passed through. Similarly, the central ray h from 41b
b is caused by the inclined surface 42b, the central ray hd from 41d is caused by the inclined surface 42d, and the central ray he from 41e is caused by the inclined surface 42e, as if P. It is bent as if it had passed through. Note that the central ray hc from 41c passes through the plane 42c perpendicularly, and P is on the extension line of this central ray ha. exists. In this way, an inclined plane with a defined angle of inclination is provided corresponding to each light emitting section, and the prism 42
The direction of the central ray of each luminous flux after being emitted from Po is controlled as if it were emitted from Po. This P. As described above, is maintained conjugate to a desired position P (not shown) near the deflection/reflection surface via the optical system.

Problems in this case include the precision and method of microfabrication of the prism 42, the alignment and bonding method between the prism 42 and the array laser 41, and the smaller the pitch of the array laser, the more difficult it becomes. In fact, it is almost impossible if the thickness is less than 100 μm.

On the other hand, FIG. 5 shows an attempt to have a similar effect with an optical system, that is, a relay optical system 53, with array lasers 51a, 5
This is an example in which a relay optical system 53 is interposed between a collimator lens 52 and a cylindrical lens 55, which collimate the light emitted from 1b and form an image, and the image is formed on a polygon 54. The image is formed on a surface (not shown).

The problem in this case is the optical path length, and the relay system itself is approximately 2
It becomes 0cm longer.

On the other hand, in order to solve the above-mentioned problems, Seito Hondade published Japanese Patent Application No. 59-240418, Japanese Patent Application No. 60-424, etc., in which a plurality of semiconductor lasers are monolithically formed, and each semiconductor laser is A semiconductor device has already been proposed in which the laser beams are emitted in different directions.

[Summary of the invention]

An object of the present invention is to provide a semiconductor laser device that can be easily manufactured and that can be combined with lenses etc. to construct an optical system with a short optical path length. This will further improve the

A semiconductor laser device according to the present invention is a semiconductor device in which a plurality of semiconductor lasers are monolithically formed.
A feature of the above-described semiconductor laser is that the respective directions of light emission are different when the light is emitted from the respective resonant surfaces of the semiconductor laser.

Note that the expression "the directions of light emitted from each laser are different" used in the following description does not mean that there are no sets of lasers that emit light in the same direction, but in a broad sense, there is one set of lasers that emit light in different directions. This means that there are more than one set.

The problem with integrating a large number of semiconductor lasers at high density is that the emission efficiency decreases due to the heat generated by carrier injection for oscillation and temperature rise, and it is no longer possible to obtain a constant optical output with a constant injection current. It disappears. This is serious when a semiconductor laser is used as a light source in an optical recording device, leading to recording errors and deterioration of recording quality.

In order to prevent the above-mentioned reduction in luminous efficiency, the specific solution proposed in the present invention is to connect each semiconductor laser to a stacked semiconductor of the same conductivity type, including the active layer, and a semiconductor laser of the opposite conductivity type. This is achieved by implanting impurities forming a conductivity type to form a striped pn junction and improving the light emitting characteristics. That is, by adopting the above structure as described in the examples below, (I) the injection current required for light emission is reduced, the amount of heat generated to obtain the same level of light output is small (and the operating temperature is lower). (Become.

(2) Good 8 degree characteristics, with little fluctuation in light output even when operating at high temperatures.

(3) There is little variation in performance between adjacent elements, and homogeneous output can be obtained from a plurality of output ends.

(4) It became possible to take out the electrode from one plane.

Due to the above-mentioned combined effects, good light emission characteristics can be obtained regardless of the light emission history in the obliquely emitting array laser that is highly integrated as in the present invention.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 11 to 15 indicate individual semiconductor lasers, and 11a to 15a correspond to a current injection region, that is, a light emission region in each semiconductor laser 11 to 15. The angles formed by the extension lines of the injection regions 11a to 15a (hereinafter referred to as resonance directions) llb to 15b and the normal line 18 erected to the resonance surfaces 16 and 17 are φa, φb, φC2φd, and φe, respectively. It is formed like this.

Note that the resonance planes 16 and 17 are usually parallel because the cleavage planes of a crystal (e.g., GaAs) used as the substrate are used, but in cases such as dry etching where the degree of parallelism may be slightly different, Consider the resonant surface 16 on the laser emission front side as a reference.

When the light resonated at the resonant surfaces 16 and 17 is emitted from the resonant surface 16 as a laser beam, it is bent according to Snell's law. In the figure, 1lc-15c indicates the light emission direction.

Here, if the angle between an arbitrary light emission direction and the normal line 18, that is, the emission angle is θ, then n/n0=sinθ/sin
The relationship φ holds true. For example, considering the case where the light is emitted from a GaAs crystal, n (the refractive index of the crystal) is 3.5 and nO
(The refractive index of air) is about 1, so if φ is chosen to be 1 degree, the laser beam will be emitted at an angle of about 3.5 degrees with respect to the normal 18.

In the embodiment shown in FIG. 1, φa, φb, φC1φd,
By setting φe to +1.0 degree, +0.5 degree, 0.0 degree, -0.5 degree, and -1.0 degree, the output angles θa, θb, θC2θd, and θe are respectively +
3.5 degrees, +1.75 degrees, 0.0 degrees, -1.75 degrees.

We were able to create an array laser with an angle of -3.5 degrees.

FIG. 6 is a sectional view taken along line A-A' in FIG. 1.

The manufacturing process will be described in detail below using this figure.

FIGS. 6(a), (b), and (c) show examples of the present invention. Here, (c) is an overall view, and (b) is a view seen from the direction of the resonator surface. (a) shows the structure of the crystal. In figure (a), 101 is a substrate, and a high resistance GaAsWater is placed on top of this. o, 3 Gao, 7As from 1 to
5 μm This is used as a cladding layer. Next, l'03's n
- GaAs layer of 0.35 μm and 104 cladding layers n-Al! . , 3 G,), 7 As of 1.5 μm1 and a cap layer of n-G a As of 1 to 3 μm thereon.
Form. 102 and 104 each n-Aj! 0.3
Ga6.7As is a light source in the 103 n-GaAs layer.

Lock up your carrier. Next, in order to obtain the structure shown in FIG. 2(b), it is necessary to diffuse Zn. S
A diffusion mask is formed using i3 N4 and Zn is diffused. The carrier concentration of the diffusion part 112, which forms the diffusion parts 112 and 113 by double diffusion, is l x 1020 cm.
The carrier concentration of -3,113 is I x 1019 cm-
It should be about 3. As a result, area 112. 113 is a P type region. This is the active layer. A current flows horizontally through 103, and light is emitted from the ll1 portion. In FIG. 2(b), 106 is P-GaAs which has been made into P type by Zn diffusion. 105 is GaAs which remains as n-type. each electrode 108,
107 and P type of 108 respectively are Au-Cr107
For the n-type, Au-Ge-Ni/Au was used. When this example is viewed from the top as shown in Figure (C), the crank is located at 110. This crank has the effect of reducing absorption of laser light near the end face during laser oscillation. Therefore, it has the advantage of high output.

In this example, Zn is used as the diffusion source, but Si may also be used.

In that case, the entire P-type layer is formed, and Si is diffused to form a P-type layer.
This forms an N junction. In addition, although a crank type was used in this example, Zn was also used near the end face without forming a crank.
A diffused laser is also good.

In the semiconductor device according to the present invention, array lasers with different light emission directions are created using cleavage planes, but the present invention is not limited to array lasers using cleavage planes. Depending on mounting considerations, it is also possible to employ, for example, a resonant surface formed by a wet process or a dry process on one side or both sides. Examples are shown in Figures 2-1 and 2-2.

213a to 213e, 223a in each figure
223c is an injection region, each having an independent injection electrode. 214a to 214e, 215a-21
5e (b.

(c, d not shown) are the resonator surfaces formed by etching. Also, in Figure 2-2, 224 a
.

224b, 224c, 225a, 225b,
225c is a resonator surface formed by etching.

It should be noted that the first semiconductor layer, which is the active layer shown in the claims, and the second semiconductor layer sandwiching the first semiconductor layer are the active layers. In the third semiconductor layer structure, the second. The third region includes a superlattice structure that is not an active layer and a semiconductor layer whose composition is continuously changed;
A generation layer is a region where carrier recombination mainly occurs and a region of several thousand Å formed adjacent to the region where carrier recombination occurs.
It also contains a thin layer of: For example, a single quantum well (and multiple quantum wells, and a typical layer of about 0.1 μm)
It contains a thin layer of 0.1 μm or less that causes light confinement, such as barrier eyebrows of several to several thousand people formed on both sides of the screen.

〔Effect of the invention〕

As explained above, the present invention has made it possible to extract high luminous efficiency (and homogeneous output with good reproducibility from each laser in different emission directions) in a conventional semiconductor laser device. Since the light emitting directions are different, laser beams from many points can be imaged well on the medium using a scanning optical system, and this is extremely advantageous as a light source for optical devices such as laser beam printers.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of a semiconductor device according to the present invention, FIGS. 2-1 and 2-2 are plan views showing modified examples of the present invention, and FIG. 3 is a plan view showing a semiconductor device according to an embodiment of the present invention. Figure 4 shows a conventional example in which an array laser with a constant output direction and a prism are combined to have different output directions, and Figure 5 shows an attempt to correct an array laser with a constant output direction using an optical system. FIGS. 6(a), 6(b), and 6(c) are schematic cross-sectional views each showing an example of the configuration of a semiconductor laser. 11-15... Semiconductor laser, 16, 1
7...Resonance surface. (C)

Claims (1)

[Claims] (I) A plurality of semiconductor lasers are monolithically formed, and each semiconductor laser includes an active layer and an impurity forming a conductivity type opposite to the conductivity type in the stacked semiconductors of the same conductivity type. 1. A semiconductor laser device comprising: forming a stripe-shaped p-n junction by implanting a pn junction; the angle between the direction of the stripe and a resonant surface is varied depending on the semiconductor laser, and a plurality of lights are emitted in different directions.