JPS5886789A - Semiconductor laser photodetector photointegrated element - Google Patents

Abstract

PURPOSE:To improve the photodetecting sensitivity by composing a photodetector of a P-N junction laser and a photoconductor when a buried hetero structure semiconductor laser and the photodetector are arranged in parallel with each other as a photointegrated element, and connecting them in series with each other. CONSTITUTION:An N type InP buffer layer 102, an InGaAsP active layer 103, a P type InP clad layer 104, and a non-doped InGaAsP layer 105 to become a photoconductor are laminated on an N type InP substrate 101 having (011) plane, and are epitaxially grown. Then, mesa stripes 106, 107 for laser and detector are formed in parallel with the direction (110) by photoresist technique. In this structure, the layer 105 is lacked on the upper surface of the stripe 106. Thereafter, P type and N type current block layers 108, 109 are grown without presence on the stripes 106, 107, the P type InP buried layer 110 is grown on the overall surface, and a proton implanted insulating layer 114 is used to shield between the stripes 106 and 107.

Description

[Detailed description of the invention] The present invention relates to a buried heterostructure semiconductor laser.

The present invention relates to a semiconductor laser/photodiode optical integrated device in which a photodetector including a photodiode and a photoconductor is integrated on the same semiconductor substrate.

In recent years, the quality of optical semiconductor devices and optical fibers has improved, and optical 7
As the practical application of I-μ communications progresses, a new research field called optical integrated circuits is developing. 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. As one of these, the inventors of the present application disclosed in Japanese Patent Application No. 56-25836 that a buried heterostructure semiconductor laser (hereinafter abbreviated as BH-LD) and a PN junction photodiode (
Hereinafter abbreviated as FD. ) were integrated in parallel on the same substrate. In this optical element, BH-
The laser output light from the side of the active layer of the LD can be monitored by the PD formed on the side, and compared to the one using an etched cavity surface, the laser cavity rkJ is formed by a normal cleavage technique. So what is the performance of BH-LD? It has the characteristic of not being damaged at all. By applying a positive bias to the BH-LD in this optical element and flowing a current to cause laser oscillation, and applying a negative bias to the PD via an external resistor, the laser light output can be monitored. However, in this example, since the laser scattered light from the side surface of the active layer of B) l-LD is weak, the light receiving sensitivity cannot necessarily be said to be sufficient.

An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide a BH-LD with improved light-receiving sensitivity, in which a BH-LD, a photodetector consisting of seven otoconductors, and a photodiode are arranged in parallel.
An object of the present invention is to provide an LD/photodetector optical integrated device.

According to the present invention, the energy surrounding the active
In a semiconductor laser/photodetector optical integrated device in which a buried heterostructure semiconductor laser covered with a semiconductor material with a large refractive index and a low refractive index and a 7-photodetector are integrated on the same semiconductor substrate, the activity of the buried heterostructure semiconductor laser is A photodiode, a photoconductor, and a photodetector made of a semiconductor that is less sensitive to energy gear than the layer is formed on at least one side of the buried heterostructure semiconductor laser in a direction perpendicular to the laser resonance axis. A semiconductor laser/photodetector optical integrated device is obtained.

The present invention will be described below with reference to the drawings showing examples.

FIG. 1 is a sectional view of an optical integrated device according to the present invention. To obtain such a device, first, an n-InP buffer layer 102 is formed on a (001) n-InP substrate 101, and an emission wavelength of 1
．． I n6 corresponding to 3 μm? tG 863g A B
OJI P6) *Active layer 103, p-InP cladding layer 104, non-doped corresponding to emission wavelength 1.44 m”@
U Ga63@ASOJI P(1,18 layer 105(
A mesa stripe 106 for a BH-LD and a mesa stripe 107 for a photodetector are formed in parallel to the <110> direction on a semiconductor structure 7A in which layers (thickness 2 μm) are sequentially laminated using a normal photoresist technique. . At this time, the non-dawg In61110m, which becomes the photoconductor,
As, ), PtIJI layer 105 is In6. q
Ga63@A'%ntP6J. The active layer 103 is also made of a semiconductor material with a small energy gap.
, i1 above the mesa stripe for BH-LD [iFi this I
n6JIGg, ), A”IIJIP (LSI layer 10
It is essential that it does not contain 5. Embedded growth is performed on the semiconductor wafer with mesa stripes formed in this way. The buried layer 110 is n-Ina with an emission wavelength of 1.1 μm.

"e,ts The ASaJ self-pox'r electrode layer 111 is grown continuously over the entire surface. In this optical device, the BH-
The LD 151 and the 7-point protector 152 are electrically insulated by the proton injection insulating layer 114, and the BH
- Laser output light could be monitored by applying a positive bias to the LD 151 to cause current to flow, causing laser oscillation, and applying a negative bias voltage to the photodetector 152 via an external resistor.

In the embodiment of the present invention, the photoconductor 152F
This is achieved by connecting an iPN junction type PD in series with a photoconductor with low impurity a degree, which has a low resistance when not irradiated with light, and by forming the photoconductor directly above the PD in this way.

We were able to receive even more weak scattered light from the laser.

In the embodiment of the present invention, an optical semiconductor element with a wavelength of 1 μm using InP as a substrate is shown, but the material is not limited to this material, and other materials may be used without any problem. In addition, an InGaAsP layer with a large energy gap may be used as the current blocking layer instead of the InP layer and the active layer. In that case, this scrap serves as a light guide layer, further improving the light receiving efficiency. You can expect that.

The percent feature of the present invention is that in an optical integrated device in which an HH-LD and a 7-meter detector are arranged in parallel, the photodetector is composed of a PN junction type PD and a photoconductor; Since the conductor was formed, the light receiving sensitivity e could be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an optical integrated device according to the present invention. In the figure, 1011in-InP substrate, 102 is n-InP buffer layer, 103 is In6. q G m(1, HA
IIIJI P6g active layer. 104 is a p-InP cladding layer, and 105 is a non-doped I noJt GaOM A that becomes a photoconductor.
1 (Lll Po, 11 layers, 106Fi, B) i-LD
107 is a mesa stripe for 7 Oto detector, 108 ijp-1nP@1 style pro, layer, 109 is n-InP current pro, layer, 110 is p-I
nP buried layer, 111F'i, n I n611
G aO,tl A 8631 P6jy electrode layer, 11
2, 113 is a Zn diffusion layer, 114 is a proton injection insulating layer, 115 is a Sin insulating film, 116, 117 is a p-type ohmic electrode, and 118 is an n-type ohmic electrode.

Claims (1)

[Claims] A semiconductor laser/photodetector optical integrated element in which a buried heterostructure semiconductor laser in which the active layer is surrounded by a semiconductor material with a large energy gap and a low refractive index and a seven-point detector are integrated on the same semiconductor substrate. , the photodetector including a photodiode made of a semiconductor having an energy gap not larger than the active level of the buried heterostructure semiconductor laser and an otoconductor is perpendicular to the laser resonance axis of the buried heterostructure semiconductor laser. A semiconductor laser/photodetector optical integrated element, characterized in that it is formed on at least one side in an outward direction.