JPS5931872B2 - Optical semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical semiconductor device that integrates a semiconductor light emitting element and a semiconductor photodetector element for monitoring the light emission thereof.

2. Description of the Related Art A so-called photocoupler is a semiconductor device that integrates a semiconductor light emitting element and a semiconductor photodetecting element.

This is clear from the fact that the pixel element is arranged so that the semiconductor detection element receives as much light as possible from the semiconductor light emitting element, and is also used to electrically separate two electric circuits. In addition, the pixel elements are arranged to be completely electrically isolated. This invention differs from a photocoupler in that it integrates a semiconductor light-emitting element whose output light is extracted to the outside and is used for a desired purpose, and a semiconductor light-detecting element for simply monitoring its light-emitting state. , this type of semiconductor device has not yet been produced.

If the light-emitting element and the photo-detecting element are to be mounted integrally on the base of the package, common sense suggests that the pixel element should be mounted so that the light-receiving surface of the photo-detecting element is perpendicular to the light from the light-emitting element. It will be placed. For example, the light emitting element is a pn junction element and emits light parallel to the pn junction surface,
If the photodetector element is also a pn junction element, the pixel elements will be mounted so that the pn junction planes are orthogonal to each other. However, it is not easy to mount the light emitting element chip and the photodetecting element chip on a flat mounting base so that they are perpendicular to each other, and even if they can be mounted, it is difficult to take out the lead wires. On the other hand, in the case of semiconductor lasers and high-intensity light emitting diodes, the optical output is 100m.
Although there are some devices that exceed W, in the case of silicon pn junction diodes and silicon pin photodiodes, even if the light receiving area is 10 mmφ, the straight line of the photoelectric conversion characteristic is maintained at about 10 mW at most.

Considering this point, in order to monitor the light of a light emitting element, it is not necessarily necessary to arrange the photodetector element so that it receives as much light as possible, as in a photocoupler, but to ensure that only a portion of the emitted light is received. It is sufficient if it can be detected. In view of the above-mentioned points, the present invention provides a compact package in which a semiconductor light emitting element whose mounting process and lead wire extraction process are easy, and whose output light is used for a desired purpose, and a semiconductor photodetector element which monitors its light emitting state. The Company provides an optical semiconductor device integrated with the above.

That is, in the optical semiconductor device according to the present invention, an edge-emitting type semiconductor light emitting element and a semiconductor photodetecting element for monitoring the light emission state of the semiconductor light emitting element are mounted on a package base, and the light emitted from the light emitting element is disposed on the package base. Mounted in layers so that the central axis is parallel to the light-receiving surface of the photodetection element, and a part of the light emitted from the light emitting element with a certain spread is incident on the photodetection element. It is characterized by what it did.

An embodiment of this invention is shown in FIG. This is an example in which a semiconductor laser element with a GaAs-GaAtAs double heterojunction structure is used as a semiconductor light emitting element, and a silicon Pn junction photodiode is used as a semiconductor photodetector element. That is, the silicon Pn junction photodiode 1 has a shallow Pn junction surface 12 formed on its light-receiving surface 11 side, and the n-side ohmic electrode 12 is provided on the entire surface.
It is mounted on the package base 3 with the side ohmic electrode 13 facing down. Is the p-side ohmic electrode 14 of this photodiode 1 disposed on a part of the p-layer surface? A GaAs-GaAtAs double heterojunction semiconductor laser device 2 is mounted on the p-side ohmic electrode 14 so that its Pn junction surface 21 is parallel to the light-receiving surface 11 of the photodiode 1. In this case, the p-side ohmic electrode 22 of the semiconductor laser device 2 is placed downward, and this
It is mounted with such polarity that it comes into contact with the p-side ohmic electrode 14 of. Then, the common p-side lead wire 41 of the photodiode 1 and the semiconductor laser device 2 is taken out from the p-side ohmic electrode 14 of the photodiode 1, and the n-side lead wire 42 is taken out from the n-side ohmic electrode 23 on the surface of the semiconductor laser device 2. ing. In other words, photodiode 1
and a semiconductor laser element 2 are stacked and mounted in layers so that their Pn junction surfaces are parallel to each other and one electrode is substantially shared. When the semiconductor laser element 2 and the photodiode 1 are integrated in this way and current is injected into the semiconductor laser element 2, laser beams 51 and 52 are emitted from the two opposing end faces of the laser element 2 to the Pn junction surface 21, respectively. It is emitted with a spread angle of 50 degrees in the vertical direction and with a spread angle of 10 degrees in the direction parallel to the Pn junction surface 21. These laser beams 51, 52
A portion of one of the laser beams 51 has a large spread angle and therefore enters the light receiving surface 11 of the photodiode 1 arranged parallel to the central axis of the laser 51. The proportion of the emitted laser light 51 that is received by the photodiode 1 is:
The length of the light-receiving surface 11 of the photodiode 1 in the laser beam emission direction, from the light-receiving surface 11 to the Pn junction surface 2 of the semiconductor laser element 2
It can be set arbitrarily by changing the height etc. up to 1, and the light emission output intensity of the semiconductor laser element 2 can be monitored by this photodetection output. Most of the laser beams 51 and 52 from the semiconductor laser element 2 are directly extracted to the outside as optical output and used for desired purposes.
As described above, if the semiconductor laser element and the photodiode are mounted in a layered manner, the mounting process is obviously simpler than, for example, when one is mounted perpendicular to the other.

Furthermore, the work of attaching lead wires to each element electrode by wire bonding or the like becomes easier because the electrode surfaces of the pixel elements are parallel. Since the two elements are stacked on top of each other in a layered manner, there is also the effect that the overall size can be reduced.

As a specific example, in the configuration shown in FIG. 1, GaAs-GaAtAs
Optical output of double heterojunction semiconductor laser device 2 is 10m
W, and the light-receiving surface 1 of the silicon Pn junction photodiode 1
When the area of photodiode 1 was 2 mm x 51 Lm, a current of 0.8 mA was obtained as the output of photodiode 1.

Furthermore, as a result of observing the laser beam 51 from behind, interference fringes caused by reflection from the light-receiving surface 11 appeared in the radiation pattern, but the beam spread angle of the laser beam 51 was larger than the original spread angle. No change was observed, and the optical output was 8 mW. In this way, the photodiode 1 can obtain sufficient output to monitor the emission intensity of the semiconductor laser element 2, and the laser beam 51 emitted to the photodiode light receiving surface 11 side of the semiconductor laser element 2 can be used not only for monitoring purposes. , it was possible to extract a sufficiently large laser light output. FIG. 2 shows another embodiment of the invention, in which parts corresponding to those in FIG. 1 are given the same reference numerals as in FIG.
In this example, the Pn junction surface 12 of the photodiode 1 is formed only on the lower part of the light receiving surface 11, and the semiconductor laser element 2 is formed on the n-side ohmic electrode 13'' on the n-type conductive layer of the photodiode 1.
It is placed on top of the . Therefore, photodiode 1 in FIG.
A p-side ohmic electrode 145 corresponding to the p-side ohmic electrode 14 is arranged at the periphery of the light-receiving surface 11. With this structure, the n-side ohmic electrode 13 of the photodiode 1
, 13' and the p-side ohmic electrode 2 of the semiconductor laser element 2.
2 can be electrically connected to the base 3 and grounded. FIG. 3 is a modification of FIG. 2, and parts corresponding to those in FIG. 2 are given the same reference numerals as in FIG. 2.

This is a step formed by mesa etching between the light receiving surface 11 of the photodiode 1 and the surface on which the semiconductor laser element 2 is mounted. When the detection sensitivity of the photodiode 1 is high, only a small portion of the laser beam 51 is absorbed by the light-receiving surface 11, and by providing a step in this way, the proportion of the light-receiving surface 11VC absorbed can be reduced. The light 51 can be extracted as a sufficiently large optical output. In this case, by changing the level difference, the proportion of human radiation onto the light receiving surface 11 can be arbitrarily set. FIG. 4 shows still another embodiment, in which the mounting order of the photodiode 1 and the semiconductor laser element 2 shown in FIG. 1 is changed.

In this example, a light-transmitting insulator 6 is interposed between the light-receiving surface 11 of the photodiode 1 and the base 3 in order to stably hold the photodiode 1. In this case as well, the light that leaks from the light-transmissive insulator 6 out of the laser light 51 is a component with a large spread angle and is lost, and the laser light component that travels straight on a plane parallel to the light-receiving surface 11 passes through the light-transparent insulator 6. Because it passes through,
A certain proportion of the laser beam 51 can be received by the Hoy diode 1. The light-transmitting insulator 6 may have a waveguide structure such as a slab waveguide or an optical fiber, or may be a simple glass plate. Further, such a light-transmitting insulator may be placed on the light-receiving surface 11 of the embodiments shown in FIGS. 1 to 3. Note that in the above embodiments, GaAs-GaAt is used as the semiconductor light emitting device.
Although an As double heterojunction semiconductor laser device is used, any light emitting device may be used as long as it has a so-called edge-emitting structure in which light is emitted in a direction parallel to the electrode surface. Further, the semiconductor photodetecting element is not limited to a silicon Pn junction photodiode, but other elements such as a pin photodiode, a shot key barrier photodiode, an avalanche photodiode, etc. can be used. As explained in detail above, according to the present invention, the mounting process and the lead wire extraction process are easy, and the edge-emitting type semiconductor light emitting element whose output light can be used for a desired purpose and the semiconductor device that monitors its light emitting state are provided. It is possible to provide an optical semiconductor device in which a photodetecting element is integrated into a compact package.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an example of an optical semiconductor device according to the present invention, FIG. 2 is a schematic perspective view showing another embodiment, and FIG. 3 is a schematic perspective view showing a modification of FIG. 2. FIG. 4 is a schematic sectional view showing still another embodiment. 1... Silicon Pn junction photodiode, 11...
Light receiving surface, 12...Pn junction surface, 13, 13'...n
Side ohmic electrode, 14,14''...p side ohmic electrode, 2...GaAs-GaAtAs double heterojunction semiconductor laser element, 21...Pn junction, 22...
p-side ohmic electrode, 23...n-side ohmic electrode,
3... Package cage base, 41, 42... Lead wire,
51, 52... Ray light, 6... Light-transmitting insulator.

Claims (1)

[Claims] 1. On a package base, an edge-emitting semiconductor light emitting element whose output light is used for a desired purpose and a semiconductor photodetector element for monitoring its light emission state are placed on a central axis of light emitted from the light emitting element. are mounted in layers so as to be parallel to the light-receiving surface of the light-detecting element, and a part of the light emitted from the light-emitting element with a certain spread is made to enter the light-detecting element. An optical semiconductor device characterized by: