JPS60193393A - Optical integrated circuit device - Google Patents

Abstract

PURPOSE:To enable to perform a modulating operation in a highly accurate manner by a method wherein a layer, with which the light emitted by an active layer will be diffused, is provided between a substrate and the band gap layer of the size same as or smaller than that of the band gap of a laser part, and the laser part and a transistor part are separated to each other. CONSTITUTION:An n type InGaAsP layer 30 is formed between the n type InGa AsP substrate 1 of an optical integrated circuit device and an n type InP buffer layer 2, and resin 16 is buried until it reaches a layer 30. Using said layer 30, a prescribed band gas is formed in the direction as shown by an arrow 21 in the diagram, the light emitted from an active layer 3 is absorbed by the layer 30, and the light is prevented from reaching a transistor TR part. Also, the light making progress in horizontal direction is absorbed by the resin 16 shown by the arrow 22 in the diagram, and the light is prevented from reaching the TR part. Then, the laser part and the TR part are completely separated, and the adverse effect which will be given to the TR part by the light emitted from the laser part is eliminated, thereby enabling to perform a modulating operation in a highly accurate manner.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a light emitting device used in optical fiber communications and the like.

Conventional configurations and their problems With the remarkable development of optical fiber communications, it is expected that the light emitting devices used as light sources will have higher performance. Semiconductor lasers are mainly used as light-emitting devices, but recently, light-emitting devices that integrate a semiconductor laser and its driving circuit on the same substrate have been reported. It is superior in terms of low noise and high reliability.

FIG. 1 is a sectional view of an integrated device in which a hetero bipolar transistor is formed in the buried layer of a conventionally reported buried structure semiconductor laser. n-type InP buffer layer 2.
n-type InGaAsP active layer 3. The region formed by the p-type InP cladding layer 4.1) type InGaAsP:17 tact layer 6 is the laser section, and the p-type InP separation layer 6. n-type InP=+rector layer7. p-type InGaASP base layer 8. The buried layer made of the n-type InP emitter layer 9 serves as the transistor 7S15. In order to electrically and optically separate the laser section and the transistor section, a resin 16 is embedded between the laser section and the transistor section.

In such a conventional integrated device, the laser part has a buried structure, so the drive current is small (Ith<3omA).
) It has a single and stable transverse mode, and the transistor part has a hetero-bipolar structure, so it can be driven at low voltage and high current (III≧somA). This has the disadvantage that it affects the characteristics of the transistor.

To explain this in detail, the light emitted by the active layer 3 of the laser section has a wavelength of λ-1.3 μm, so it is transparent to the InP layer where λg = o and 9 μm. be. Therefore, the light emitted from the active layer 3 is not absorbed by the InP layer, but is reflected by the mu/Sn electrode 18 on the substrate side, and enters the transistor section as indicated by the arrow 2o. The base layer 8 of the transistor section has a band gap λg = 1+3
μm +7) Since it is formed of InGaAsP, it absorbs the incident light of λ=163 μm and generates electrons and holes. These electrons and holes are transferred to the collector layer 7.
．． Since it flows into the emitter layer 9, the collector current of the transistor increases. That is, the collector current changes in proportion to the emission intensity of the laser section. This is very inconvenient in a modulation operation in which the laser section is driven by a transistor and the laser beam is modulated.

As described above, the conventional structure has the drawback that the light emitted from the laser section affects the transistor characteristics, causing operational problems.

OBJECTS OF THE INVENTION In view of the conventional drawbacks as described above, the present invention provides an integrated device having a structure in which the laser section and the transistor section are optically completely separated.

Structure of the Invention The present invention forms a layer between the active layer and the substrate with a band gap that is the same as or smaller than the band gap of the active layer of the laser section, so that the light emitted by the active layer is absorbed by that layer. This is an integrated device characterized by the following.

Description of examples FIG. 2 is a cross-sectional view of an embodiment according to the invention.

Between the n-type InP substrate 1 and the n-type InP buffer layer 2,
It has a structure in which a type 1nGaAsP layer 30 is formed. Further, the resin 16 is embedded until it reaches the n-type InGaAsP layer 30. In such a structure, the active layer 3
The light of λ-1.3μm emitted at λ
InGILA with a bandgap of g = 1.3 μm
Since it is absorbed by the SP layer 30, it does not reach the transistor part. Also, the light traveling in the horizontal direction is absorbed by the resin 16 as shown by the arrow 22, so it does not reach the transistor part. No. According to experiments, InGaM 8P
If the thickness of Jso 30 is 1 μm or more, it will absorb enough light,
It was found that there was no effect on the transistor section.

Therefore, according to this structure, the laser section and the transistor section can be completely optically separated, so that the light emitted from the laser section does not affect the transistor section, and stable transistor operation can be performed. That is, when a transistor is used to drive the 1-the part to perform a modulation operation, stable transistor operation can be performed, so no problems occur, and a highly accurate modulation operation becomes an rj function.

Furthermore, this structure has the advantage that it is only necessary to increase the number of epitaxial layers, and that all other processes can be performed in the same way as conventional methods.

Effects of the Invention As described above, in the integrated structure according to the present invention, the light emitted from the active layer can be used to perform a transistor operation, and a modulation operation with good sheath expansion is possible. In addition, in terms of process, it is only necessary to increase the number of epitaxial layers, and there is an advantage that it can be manufactured using almost the same process as the conventional method.

[Brief explanation of drawings]

FIG. 1 is a structural sectional view of a conventional buried structure semiconductor laser and hetero bipolar transistor integrated device, and FIG. 2 is a structural sectional view of an integrated device according to an embodiment of the present invention. 11...n BlInPg board, 2...
n W InP buffer layer, 3... n-type In
GaAsP active layer, 4..., p-type InP cladding layer, 6...p-type InGaAsP contact layer, 6...p-type 1nP isolation layer, 7...
・N-type InP collector layer, 8...p-type! nGa
A+sP base layer, 9...n-type InP emitter layer, 10...p-type InP diffusion layer, 11...
...SiO2 insulating film, 12...Muu/Zn electrode, 13...Ti/Pd/MuU% electrode, 16...
...Resin, 18, ...Muu/an electrode, 2
0,21.22...The direction of light'1)

Claims (1)

[Claims] A light emitting element and another element are formed on the same substrate, and a layer having a band gap that is the same as or smaller than that of the active layer of the light emitting element is formed between the active layer and the substrate. Optical integrated circuit device.