JPS61159783A - Semiconductor device - Google Patents

Abstract

PURPOSE:To monitor optical beams from each light-emitting element efficiently, and to adjust the amount of light of the optical beams precisely by fitting a photodetector at an intersection in the beam projecting directions of each of a plurality of the light-emitting elements. CONSTITUTION:Several laser diode 1-3 and a photodetector 4 are formed onto the same substrate 5 in a monolithic manner. Projecting end surfaces 1a-3a in respective laser diode 1-3 are positioned onto the same circumference, and shaped so that a light-receiving surface for the photodetector 4 is positioned at an intersection P in the beam projecting directions 1c-3c. According to such constitution, beams from the laser diodes 1-3 can be received efficiently by one photodetector 4, thus controlling the amount of light from several laser diode 1-3 with higher accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device in which a plurality of semiconductor light emitting elements are formed in a seven-dimensional array.

[Conventional technology]

Conventionally, when designing an optical scanning device using a plurality of semiconductor lasers or light emitting diodes (LEDs), as disclosed in JP-A-59-128, for example, the light emitted from the light emitting body is The light sources are arranged so that the emission directions of the two intersect at one point Pa, so that a scanned surface (not shown) can be scanned with a plurality of scanning spots while maintaining a good image formation state.

FIG. 5 shows a typical conventional example, and shows the optical system between the light source and the deflector viewed from a direction perpendicular to the deflection scanning plane. 51a and 5fb are semiconductor lasers, and each laser is arranged on a mount 52 so that its light beam generating surface is parallel to the end surface of the mount 52. Mount 5 provided with semiconductor lasers 51a and 51b
The end surfaces 52a and 52b of 2 are the center rays ha of the diverging light beams from the respective lasers 51a and 51b.

hb is set as if it had passed through the same point Po. In other words, when normal lines are drawn to the end faces 52a and 52b at the positions where the semiconductor lasers (51a, 51b) are provided, the end faces 5 are aligned so that each normal passes through Po.
2a and 52b are set. Furthermore, when viewed from a direction parallel to the deflection scanning plane, the central ray h of each semiconductor laser
The position of the semiconductor laser provided on the mount 52 is set so that the position of a and hb passing through point Pa is slightly displaced in a direction perpendicular to the deflection scanning plane. Above P
Point a and a point P in a predetermined vicinity of the deflection reflection surface 53 of the deflector are maintained in an optically conjugate relationship by the imaging lens 54.

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 devices, but the term also applies in principle to light emitting devices 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 a seven-ray laser.

[Problem that the invention seeks to solve]

In the conventional semiconductor devices described above, there is no example in which the light intensity is adjusted for each light emitting element, and in most cases where light emitting elements are formed by cleaving a normal crystal, a light receiving element is provided corresponding to each light emitting element. . Therefore, in this case,
There is a drawback that as the number of elements increases, it becomes difficult to accurately match each light emitting element to each light receiving element.

On the other hand, there are examples in which only one light-receiving element is provided for each light-emitting element by cleavage, but there is a drawback that as the number of light-emitting elements increases and the pitch increases, the accuracy of light intensity adjustment deteriorates.

It is an object of the present invention to eliminate alignment errors and limitations on integration density caused by arranging semiconductor light emitting devices in a hybrid, and also to eliminate alignment errors and limitations in integration density caused by arranging semiconductor light emitting devices in a hybrid structure, and to eliminate problems such as when using a monolithically formed array laser with a constant light emission direction. An object of the present invention is to provide a semiconductor device that makes it possible to avoid the complexity of an additional optical system.

[Means for solving problems]

In order to achieve the above object, a semiconductor device according to the present invention has a semiconductor device in which a plurality of semiconductor light emitting elements are formed on the same substrate, in which each emission end face of the semiconductor light emitting elements is formed on the same circumference. However, a photodetector is formed at the intersection of the optical axes of each of these semiconductor light emitting elements in the light emission direction.

More specifically, the light-receiving surface of the photodetector is provided with an arbitrary inclination angle on the substrate, and the semiconductor light-emitting element and the photodetector are monolithically formed.

〔Example〕

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

1 to 4 show an embodiment of a semiconductor device according to the present invention.

First, in FIG. 1, each laser diode l.

2.3 and the photodetector 4 are monolithically formed on the same substrate 5. In addition, each laser diode 1, 2.3
Output end faces 1a, 2a, 3a (or lb
, 2b, 3b) are located on the same circumference, and the light emission direction 1c of each laser diode 1, 2.3.

The light receiving surface of the photodetector 4 is located at the intersection P of 2c and 3c. Furthermore, each laser diode 1
, 2.3 and the photodetector 4 have exactly the same film structure, and if the electrical connections are reversed, they each function as a device.

The output end faces 1a, 2a, 3a of each of the laser diodes 1°2.3 thus formed and the light detection 1!4 (7
) The light-receiving surface must have a mirror surface, so if reactive ion beam etching is not sufficient, chemical etching is recommended as a finishing touch. In this example,
A sulfuric acid-hydrogen peroxide system was used as a chemical etching solution.

Next, the manufacturing process will be explained.

In FIG. 2, n-type G
aAsba, 77 Calendar 2! 1.51s, n-type GaAjlA
The S cladding layer 22 was laminated with l p , the undoped GaAs active layer 23 was laminated with Q, 5p, the P type GaAjAs cladding layer 24 was laminated with lQ, and the P type GaAs cap layer 25 was laminated with 0.5 scales.

Next, a mask is formed on the thus formed double heterostructure crystal by a photolithography process so as to obtain a desired morphology.

The mask pattern at this time is such that the light emission directions 1c, 2c, and 3c of each laser diode are shifted by 1.3 degrees, and the photodetector 4 can be configured at the intersection point P of each light emission direction. It is made.

The thus masked crystal was removed to the surface of the substrate 5 by reactive ion beam etching to obtain the shape as shown in FIGS. 1 and 3.

! FIG. 4 is a plan view of FIG. 1, showing the positional relationship between the three-beam array laser diodes 1 to 3 and the photodetector 4. In this way, since the photodetector 4 is configured at the intersection P of the light emission directions 1c, 2e, 3c of each laser diode 1, 2.3, one photodetector 4 can efficiently detect the laser diodes 1, 2.3. It became possible to receive 3 lights. Therefore, with higher precision the individual laser diodes 1,
2.3 Light amount control is now possible.

Next, a method for driving each laser diode will be explained with reference to FIG.

First, each electrode ld, 2 of the laser diode 1, 2.3
d and 3d are each driven independently. At this time, since it is not possible to simultaneously monitor the light, each laser diode is driven in chronological order, and the light amounts of the laser diodes 1, 2.3 are stabilized by comparing each with a reference value. Note that this stabilization operation is performed, for example, during idle time unrelated to image recording.

Furthermore, in the positional relationship between the laser diode 1.2.3 and the photodetector 4, the optical axis beam with the maximum intensity of the radiation beam from the laser diode is located at the output end face 1a, 2a.
, 3a, each laser diode 1, 2.3 causes self-coupling, resulting in unstable characteristics. Therefore, the light beam is transmitted to the output end face 1a of itself (e.g. l) and the other laser diodes (2 and 3).
, 2a, 3a is required. That is, by tilting the light-receiving surface of the photodetector 4, that is, the surface reflecting the incident beam at an appropriate arbitrary angle, the amount of light returning to the output end surface can be extremely reduced, and the instability of the characteristics of the laser diode can be eliminated.

Regarding the direction of the light-receiving surface of the photodetector 4, (1) it can be rotated arbitrarily in a plane parallel to the surface of the substrate 5, and (2) it can be rotated at an arbitrary angle in a direction perpendicular to the surface of the substrate 5. (3) A configuration that combines (1) and (2).

Any configuration may be used.

Further, the position of the photodetector 4 is different from each laser diode 1, 2, .
From the viewpoint of light receiving efficiency, it is most preferable to install it at the intersection P of the light emission directions 1c, 2c, and 3c of No. 3, but it does not necessarily have to be at the intersection P, and even if there is some positional deviation, it will not affect the efficiency.

Further, the photodetector may be installed in a hybrid manner on the substrate of the laser diode and on the mount of the laser diode, but it requires less man-hours to form it monolithically with the laser diode.

It becomes a highly reliable composite device.

〔Effect of the invention〕

As explained above, the present invention provides a photodetector at the intersection of the light emission directions of each of a plurality of light emitting elements.
This has the effect that the light beam from each light emitting element can be efficiently monitored and the light amount of each light emitting element can be adjusted more accurately.

[Brief explanation of drawings]

Figures 1 to 4 [iii! 1 shows an embodiment of a semiconductor device according to the present invention, and FIG.
FIG. 5 is a sectional view and a plan view taken along line A', and shows an example of the configuration of a conventional semiconductor device. 1.2.3... Laser diode la, 2a, 3a... Output end face lc, 2c,
3c...Light emission direction 4...Photodetector 5...
・・・・・・・・・・・・Board Diagram 2
Evening 3rd period Figure 4

Claims (3)

[Claims] (1) In a semiconductor device in which a plurality of semiconductor light emitting elements are formed on the same substrate, each of the semiconductor light emitting elements has an emission end face formed on the same circumference, and each of the semiconductor light emitting elements emits light. A semiconductor device characterized in that a photodetector is formed at an intersection of optical axes of directions. (2) The semiconductor device according to claim 1, wherein the light receiving surface of the photodetector has an arbitrary inclination angle on the substrate. (3) The semiconductor device according to any one of claims 1 to 2, wherein the semiconductor light emitting element and the photodetector are monolithically formed.