JPS58216491A - Composite photoelement - Google Patents

Abstract

PURPOSE:To improve the reproducibility and yield of manufacturing a composite photoelement by improving the electric insulation between elements using a semi-insulating semiconductor substrate for a substrate and employing as a light source a high performance BH-LD, thereby readily forming a laser resonator surface. CONSTITUTION:In1-xGaxAsyP1-y-InPBH-LD 101 and PD 102 which are formed on an Fe-doped semi-insulating InP substrate, are opposed through an etching groove 105. One resonator surface of the BH-LD 101 is formed by an etching method. The laser output light 109 from the etching resonator surface 103 can be monitored by the photoreceiving surface 104 which is formed similarly by an etching method. In order to flow a current through the BH-LD 101, positive bias voltage is applied to the BH-LD 101 to the BH-LD electrode and the ohmic N type common electrode 108 of N type InP electrically insulated by an SiO2 insulating film 106.

Description

[Detailed Description of the Invention] The present invention provides a composite optical device in which a buried heterostructure semiconductor laser and a seven-dimensional detector are integrated on the same substrate, and in particular, the electrical insulation between the individual optical devices is improved. This invention relates to a semiconductor laser/photodetector composite optical device.

In recent years, the quality of optical semiconductor devices and optical fibers has improved, and optical fiber communications are being put into practical use.

Along with this, there is a growing trend to integrate various optical semiconductor elements in order to stabilize the system. Among these, integration of a semiconductor laser and a light-receiving element is important in terms of system configuration because of the need to monitor the optical output of a light source. High-performance buried heterostructure semiconductor laser (BH-LD)
) and a photodiode (PD) are integrated on the same semiconductor substrate, the inventors of the present application have filed a patent application filed in 1986-1.
BH-L using the etching method as shown in 29057
Invented a D-PD composite optical device. , this is ViBH-L
One resonator surface of D is formed by an etching method, and the surface opposite to it is used as the light receiving surface of PD. In this composite optical device, since the stripe width of the carrier generation region of the PD is larger than the width of the active layer of the BH-LD,
Good light receiving efficiency. In addition, the characteristics of the BH-LD are not strongly affected by etching for forming the resonator surface, and therefore the reproducibility of characteristics and manufacturing yield are relatively high.

By the way, in the above-mentioned composite optical device, in order to electrically insulate the BH-LD and PD formed on the semiconductor substrate, etching is performed to the semiconductor substrate or a semiconductor layer of the same conductivity type. ing. By doing so, a positive bias is applied to the semiconductor substrate (BH-Ll) to flow a current, a negative bias voltage is applied to the PD, and the laser output light from the BH-LD is monitored by the PI). It is now possible to do so. However, at this time, all of the current flowing through the BH-LDK does not necessarily reach the substrate side electrode, and a portion of it flows into the PD side, resulting in the observed monitor output being larger than the actual laser output light. A problem arose. That is, in the above-mentioned composite optical device, there was a problem in the electrical insulation between the BH-LI) and the PD, and the reproducibility and manufacturing yield were not necessarily sufficient.This electrical insulation was improved. As a composite optical element, a composite optical element that integrates a photodiode and a semiconductor laser on a semi-insulating semiconductor substrate and monitors the optical output of the semiconductor laser was proposed in 1972.
No. 23614, filed by Mr. Yuasa as a semiconductor device. In this invention, by using a semi-insulating semiconductor substrate, the semiconductor laser and the photodiode are certainly electrically insulated well. However, since a normal electrode stripe type semiconductor laser is used as the semiconductor laser, manufacturing is extremely difficult. There are two types of transverse mode stabilized LDs other than normal electrode striped LDs and BH structures.

Although the active layer is sufficiently thin with a thickness of about 0.1 to 0.2 μm, it is formed to extend widely in the direction parallel to the Peter junction, making the etching technique for forming the mirror surface of the laser extremely difficult. , resulting in deterioration of characteristics and reduction in yield.

An object of the present invention is to provide a composite optical device that can provide good electrical insulation between a semiconductor laser and a photodetector, and that improves the reproducibility and yield of purple sweet potato production, in order to eliminate the drawbacks of the conventional example described above. There is a particular thing.

The composite optical device of the present invention includes a semiconductor laser and a detector having the same multilayer structure on one insulating or semi-insulating substrate, and the semiconductor laser is arranged around an active layer more than the active layer. The resonator surface and the light-receiving surface of the conductor laser and the Fn) detector that face each other are formed by an etching method.
'According to the structure of the present invention, the extremely small active layer is completely surrounded by the surrounding semiconductor material of the cladding layer, so as long as the etching method for the semiconductor material of the cladding layer is mastered, it is possible to form a mirror surface. Etching is extremely easy.

Therefore, by employing BH-LD, the reproducibility and yield of device fabrication are greatly improved compared to the conventional example.

The main point of the present invention is that it is a semiconductor light emitting device that integrates a semiconductor laser and a photodetector for monitoring its optical output, and a semi-insulating semiconductor substrate is used as the substrate to provide good electrical insulation between the devices. In addition, by using a high-performance H-LD as a light source, it is possible to easily form a laser resonator surface.

Hereinafter, the present invention will be described with reference to drawings showing examples.

FIG. 1 shows a plan view of an embodiment of the present invention.

In1 formed on a Fe-doped semi-insulating InP substrate
-xGaxAs, PH-y-InP BH-LD 10
1 and PD 102 are placed opposite to each other with an etching groove 105 in between. One resonator surface of the BH-LD 101 is formed by an etching method. Laser output light 109 from this etched resonator surface 103 can be monitored on a light receiving surface 104 which is also formed by the etching method. In order to flow current through the BH-LDIOI, the ohmic nature of the n-InP electrically insulated by the electrode of the BH-LD, 8 io, and the insulating film 106 is required.
A positive bias voltage may be applied to the BH-LD 101 with respect to the shaped common electrode 108. At the same time, n-type common electrode 1
08, by applying a negative bias voltage to the PD 102, the laser output light 109 is directed to the light receiving surface 104.
It is possible to monitor the output light of the BH-LD.

2(a) and 2(b) show cross-sectional views of the composite optical device at the portions indicated by -N and BB' in FIG. 1, respectively.

To obtain such a composite optical element, first, (100)F
e A Jn-InP buffer layer 202 is formed on a doped semi-insulating InP substrate 201 by a normal epitaxial growth technique.
Non-doped In0.7 corresponding to layer forming liquid 02.3μm!
Gao, , 8Aso, , pO, 3+1 active layer 2
03. The p-InP cladding layer 204 is made sequential. The thus obtained multilayer film structure semiconductor wafer was subjected to ordinary photoresist technology and chemical etching technology (
Two parallel etched grooves 205 parallel to the 011> direction
, 206.

These two grooves only need to be rubbed with a width of 10 μm and a depth of 3 μm, and at this time, the ino and ? 2 Gao,
8ASO9Ill PG, 80 Mesa stripes 207 with a width of 2 μm including the active layer 203 are formed on both sides. A semiconductor wafer having such a narrow mesa stripe 207 and etching grooves 205 and 206 formed between the mesa stripes is buried and grown to form a p-InP current layer 22 layer 208-InP. Both of the current and current cross layer 209 are grown except for the upper part of the mesa stripe. Furthermore, p-InP buried layer 21 Q, P-I ng, 72 Ga643AS6
．． A HPo, 8@electrode layer 211 is laminated over the entire surface to complete the buried growth. BH-LD thus obtained
Etching is performed to form the wafer fan n-type electrode and to form the laser resonator surface. In addition,
As shown in FIG. 2(b), which is a cross-sectional view taken along line B-B' in FIG. It is preferable to form a Zn diffusion region 215 by diffusing Zn, which is a p-type impurity, so as to pass through the layer 209. In this case, the carrier generation region within the light-receiving surface has an effectively wide area, and the light-receiving efficiency is improved.

In order to form electrodes and etching mirror surfaces, a layer solution is first etched in a direction parallel to the mesa stripe 207 up to the n-InP buffer layer 202 in order to form an n-type electrode. Next, 8i0 for electrode separation. An insulating film 212 is formed, and a p-type ohmic electrode 213 and an n-type ohmic electrode 214 are formed so as to be separated by the insulating film 212. Next, the etching mirror surface is formed by forming a photoresist pattern as shown at 105 in FIG. etching is performed until the semi-insulating InP substrate 201 is reached using the etching mirror surface 103. What is necessary is to form the light receiving surface 104 of the PD.

BH-LDIO of the composite optical device thus obtained
By applying a positive IK bias voltage to flow a current to cause laser oscillation, and at the same time applying a negative bias voltage to the PD 102, it was possible to monitor the laser output light. As mentioned above, by using a semi-insulating substrate as the semiconductor substrate and etching the etching mirror surface to reach it, good insulation can be obtained between the BH-Ll) 101 and the PD 102, and the conventional composite optical device Compared to
The reproducibility and yield of device manufacturing have been significantly improved.

In addition, in the above-mentioned examples, %BH-LD and PD
Although the shape has been described using two parallel etched grooves and a mesa stripe sandwiched between them, the present invention is of course not limited to this. Any BH-J or D shape may be used, such as a BH-LD in which a single mesa stripe is formed and buried growth is performed, a mesa stripe, or a BH-LD in which the active layer is buried in a groove portion. When forming the etching mirror surface, etching was performed until it reached the semi-insulating semiconductor substrate, but it is sufficient to ensure sufficient insulation between elements, so etching may be performed up to the n-InP buffer layer. In addition, u InGaAs is used as a semiconductor material.
Although the explanation has been made using the P/InP system, the invention is of course not limited to this. Although the explanation has been given using a PD as a photodetector, the invention is not limited to this, and examples include an avalanche photodiode, a phototransistor, and a photoconductor.

It also includes all kinds of semiconductor photodetectors, such as those that combine these.

The feature of the present invention is that a semi-insulating semiconductor substrate is used in a composite optical device in which i, +BH-r, 1) and a photodetector for monitoring laser output are integrated on the same semiconductor reprint. This i'LK provides good electrical insulation between the BH-LD and the photodetector, and therefore the manufacturing yield is significantly improved compared to the conventional example. Of course, by using a 1000HH-LD as a semiconductor laser, device fabrication is easier than in the case of the conventional electrode stripe type LD. In particular, etching for forming a laser resonator has become easier, and the reproducibility and yield of device manufacturing have been greatly improved.

[Brief explanation of the drawing]

Figure 1 is a plan view of a composite optical element according to the present invention, and Figure 2 (
al fl A cross-sectional view of BH-I and D indicated by Chunin-A' in Figure 1, and PI indicated by B-B' in Figure 1 (Figure 2 (b))
It is in the cross section. In the figure, 101 is Bi(-, LD, 10
2ViPD, 10:3t-j etched resonator surface,
104 is a light receiving surface, 105 is an etched portion, 10
6 is an insulating film, 107 is a B, H-LJ) stripe, 1
08 is n-type 1[,109 laser output light, 201 is semi-insulating InP substrate, 202 is n-InP buffer layer,
20:lj:In6.72 Gao, 2. ASo, 1
11 Po, 1111 active layer, 204 p-InP cladding layer, 205, 206 etching s, 207 mesa stripe, 2081 dp-InP@, flow blocking layer, 209 n-InP current blocking layer %, 210 p-InP Buried layer, 211 fI:ip-Ino
,,t Gao, tsASo, 6I Po, 39 electrode layers, 212 is an insulating film, 213 is a p-type ohmic electrode,
214 is an n-type ohmic electrode and 215 is a ViZn diffusion region.・Te" 10 total Susumu Uchihara; To, + 1 time + 2 figures (cL) (b)

Claims (1)

[Claims] A semiconductor laser and a photodetector seven having the same multilayer structure are provided on one insulating or semi-insulating substrate,
A composite optical device characterized in that the semiconductor laser has a larger energy gap around the active layer than the active layer, and a resonator surface and a light-receiving surface that face each other are formed by an etching method.