JPS58100480A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To extract laser beams modulated at high speed, to miniaturize the device, to improve reliability and to reduce cost by flowing minute signal currents through a transistor element for modulation because a transistor amplifier for driving a laser is made contain into the same element. CONSTITUTION:An SiO2 film is formed onto a wafer through a sputtering method, a P type impurity is diffused up to depth reaching a semiconductor layer 4, and a first conductive type (P type) semiconductor region 11 is shaped. An ohmic electrode 15 for an N type semiconductor is formed and ohmic electrodes 13, 14 for a P type semiconductor to the surfaces of the P type semiconductor region 11 and a P type semiconductor substrate 10 respectively. A resonator at a proper interval is shaped through a means, such as cleavage, etching, etc. Accordingly, one semiconductor laser element is formed by semiconductor layers 1, 2, 3 and one NPN transistor by semiconductor layers 3, 4, 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor laser device that includes a modulation amplifier in the same element, among the components of an optical transmission system using optical fibers, in order to reduce the size of the system. .

Driving method 1 of a semiconductor laser using a light source for optical transmission and a shell is as follows.
Conventionally, the semiconductor laser element used as a light source was a single unit, so the light source and drive circuit had to be combined with each other as separate parts, making the transmitting side equipment, relay amplifier, laser drive power supply, etc. more complex, larger, and larger. This had the disadvantage of causing a decrease in reliability, etc.

In order to solve these drawbacks, the present invention has developed a semiconductor laser device having a structure in which a driving transistor amplifying meter is integrated within a semiconductor laser element.

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 shows an embodiment of the semiconductor laser device of the present invention, and FIG. 1(a) is a schematic cross-sectional view of the device, a driving circuit,
b) is the isobaric circuit C of the device.

In the figure, 1 is a conductive layer of the first conductivity type, 2 is an active layer consisting of a first or second conductivity type semiconductor layer, 3 is a second conductivity type semiconductor layer, 4 is a first conductivity type semiconductor layer, and 5 is a first conductivity type semiconductor layer. 2 conductivity type semiconductor layer, 6 a second conductivity type semiconductor layer, 7 a first conductivity type semiconductor layer, 8 a second conductivity type semiconductor layer, 9 a first conductivity type semiconductor layer,
10 is a first conductivity type semiconductor substrate, 11 is a first conductivity type semiconductor region, 12 is an insulating film, 13 and 14 are ohmic electrodes for the first conductivity type semiconductor, 15 is an ohmic electrode for the second conductivity type semiconductor, 16 1 is a signal current generator, and 17 is a DC power supply.

Next, the configuration and manufacturing method of each part will be explained. To simplify the explanation, we will explain an example in which good results were obtained by specifying the material of the semiconductor, the conductivity type, and the polarity of the applied voltage. However, the present invention is not limited to this, and it goes without saying that the present invention can also be applied to cases where the material is changed, the conductivity type, or the polarity of the applied voltage is reversed.

Here, an element using a Ga InAsP/InP-based semiconductor will be described, and the first conductivity type is p-type and the second conductivity type is n-type. That is, each reference numeral in FIG. 1 is as follows.

10: p-type InP substrate, thickness 80 μm, Zn doping, carrier density 5X1 o18 cm-5, g-P-D
5 x 1 o'cm-2.1: p-type InP layer, thickness 5 μm, Zn doping, carrier density 7 x 10''cm-'.

2' Ga0.24In0.74AS0.56PQ
, 444-element mixed crystal layer, thickness 0.2 μm, no dopant.

3: n-type InP layer, thickness 2/Jm, Te doping, carrier density 5X10Cm'.

4: p-type GaInAsP layer (convenient for stopping impurity diffusion) or p-type 1nP layer, thickness 0.5 μm.

Zn doped, carrier density 7 x 10 cm ・5: n
Type InP layer, thickness 2 μm, Te doped, carrier density 5
X10Cm'.

6: n-type InP layer, thickness 2 /j+n, Te)'
-p type, carrier density 5×10 cm−3°7: p-type InP layer, thickness 2 μn+, Zn doped, carrier density 7×10 cm−’.

8; n-type InP layer + 1.8 μm + Te doped,
Carrier density 5X10 cm a 9: p-type InP layer, thickness 2.4 μm, Zn doped.

Carrier density 7x10 cm.

In the above configuration, the lattice constants of the GaInAsP quaternary mixed crystals 2 and 4 are made to match the lattice constant of the InP single crystal.

To obtain the structure shown in FIG. 1, first, each semiconductor layer 1.2, , 4.5 are grown in this order.

In this example, a liquid phase epitaxial growth method, that is, a normal so-called slide boat method is used, and the growth temperature of each semiconductor layer (crystal layer) is between 605°C and 590°C. Next, for mesa etching of the heterojunction portion including the laser element and the transistor element, an insulating film (for example, 5i02 film, Az20. film, or 5i5N4 film) is formed on the surface using sputtering, CVD''', etc., and photolithography. etc.). In this example, an 8i02 film was formed by sputtering, and stripes with a width of 20 μm were formed using photolithography. Next, this striped thin film was etched with an etching mask. As a step, the crystals in the portions of the thin film stripes of each semiconductor layer that are not removed are removed by chemical etching or the like.

In this example, mesa etching was performed using Br2-methanol. Thereafter, each semiconductor layer 6, 7, 8.9 is sequentially grown in this order on the portion where the crystal has been removed using any of the crystal growth methods described above (liquid phase epitaxial growth method in this example). A buried layer is grown and the striped etch mask is removed to complete the wafer. After that, sputtering was performed on the wafer.

Insulating film (for example, 5i02 film, kt2 film) by CVD method etc.
05 film, 5i5N4 film, etc.) 12 is formed. In this example, an 8i502 film was formed by sputtering. Next, a part of the insulating film 12 on the semiconductor layer 5 is peeled off using photolithography technology, and p-type impurities such as Zn' and Cd are applied to the semiconductor layer 4 using means such as a closed tube method or an open tube method. the first conductivity type (p-type) semiconductor region 11
form. In this example, insulation @ (5i02 film)
A window of 5 .mu.m.times.50 .mu.m was opened in 12 using photolithography technology, and Zn was diffused by a closed tube method until it reached the semiconductor layer 4, thereby forming a p-type semiconductor region 11. Further, by using photolithography again, a part of the insulating film 12 on the n-type semiconductor crystal (semiconductor layer 5) is peeled off, and an ohmic electrode 15 for the n-type semiconductor is formed between the p-type semiconductor region 11 and the surface of the p-type semiconductor substrate 100. Ohmic electrodes 13 and 14 for n-type semiconductors are formed on each of the substrates. At this time, the electrodes 13 and 15 are separated using a lift-off method, a chemical etching method, or the like. In this embodiment, the insulating film 12 has a size of 5 μm×100
A μm window was opened, and an AuGeNi alloy was formed as the electrode 15 by vacuum evaporation. The electrodes 13 and 14 are made of Au.
A Zn alloy was formed by vacuum evaporation.

Thereafter, resonators with appropriate spacing (for example, 200 to 600 μm) are formed by cleaving, etching, or the like in a direction parallel to the paper plane of FIG. In this example, the resonator length is 2 by cleavage.
The device had a width of 00 μm2 and a width of 400 μm.

As a result of the above, one semiconductor laser element is formed by semiconductor layers 1.2.3, and one npn is formed by semiconductor layers 3 and 4.5.
) transistors (modulators) are formed.

The semiconductor laser device thus obtained was placed on a metal-coated diamond heat sink with the electrode 14 facing down.
As shown in FIG. 1(a), for the combination of electrodes 14 and 15, connect electrode 14 to positive, electrode 15 to negative, and connect DC power supply 17. For the combination 15, when the signal current generator 16 is connected to the electrode 13 as positive and the electrode 15 as negative, and a signal current is applied between the electrodes 13 and 15 corresponding to the base and emitter of the transistor, the current amplification factor of the transistor is multiplied by α. The generated current is injected into the semiconductor laser active layer 2, and laser oscillation can be obtained.

In the semiconductor laser device of this example, the electrode 15°15
When a current of 2 mA was passed between them, laser oscillation corresponding to the signal current was obtained at a room temperature of 25°C.

Its wavelength was approximately 1.53 μm. Note that the laser oscillation waveform could be observed at a repetition rate of the signal current up to 200 Mbit/s at this time.

As explained above, the semiconductor laser device of the present invention includes a transistor amplifier for driving the laser, that is, a modulator in the same element, and therefore does not require a separate modulator, and can use a small signal current for modulation. High-speed modulated laser light can be extracted by flowing it through a transistor element. Therefore, when the semiconductor laser device of the present invention is used, for example, in a repeater of the optical 1-communication system, the device can be made smaller, more reliable, and lower in cost.

Note that in order to realize the semiconductor V-za device of the present invention,
In addition to GaInAsP/InP materials, GaAAAs
/GaAs-based materials, GaAAAsSb/GaSb-based materials, etc. can also be used, and it goes without saying that color materials can also be used.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the semiconductor laser device of the present invention, and FIG. 1(a) is a schematic cross-sectional view of the device, a driving circuit,
b) is the equivalent circuit of the device. 1... First conductivity type semiconductor layer 2... Active layer 6 consisting of a first or second conductivity type semiconductor layer... Second conductivity type semiconductor layer 4... First conductivity type semiconductor layer 5... - Second conductivity type semiconductor layer 6... Second conductivity type semiconductor layer 7... First conductivity type semiconductor layer 8... Second conductivity type semiconductor layer 9... First conductivity type semiconductor layer 10...・First conductivity type semiconductor substrate 11...First conductivity type semiconductor region 12...Insulating film 13.14...Ohmic electrode 15 for first conductivity type semiconductor...Ohmic for second conductivity type semiconductor Electrode 16・
...Signal current generator 17...DC power supply patent applicant Junnosuke Nakamura, patent attorney representing Nippon Telegraph and Telephone Public Corporation

Claims (1)

[Claims] An embedded semiconductor laser diode having a transistor amplifier in the same device, wherein a Peter junction including an active layer (2) is formed on a first conductivity type semiconductor substrate (10), The structure consists of a first conductivity type semiconductor layer (
1), an active layer (2) consisting of a first or second conductivity type semiconductor layer;
), second conductivity type semiconductor layer (55 first conductivity type semiconductor layer (4)
), the second conductivity type semiconductor layer (5), and the structure of the buried crystal layer is, in order from the substrate side, the second conductivity type semiconductor layer (6).
, first conductivity type semiconductor layer (7). Second conductivity type semiconductor layer (8), first conductivity type semiconductor layer (9)
- a first conductivity type semiconductor in which a part of the second conductivity type semiconductor layer (5) is converted into a first conductivity type semiconductor by diffusion or ion implantation of impurities until it reaches the first conductivity type semiconductor layer (4);
A conductivity type semiconductor region (11) is provided, and the first conductivity type semiconductor region (11), the second conductivity type semiconductor layer (5) and the first conductivity type semiconductor region (11) are provided.
Electrodes (13) on the conductive semiconductor substrate (1o),
(15) and (14) are provided, and a signal current is passed between the electrode (16) and the electrode (15) with a DC voltage applied between the electrode (15) and the electrode (14). 2
conductive type semiconductor layer (3), first conductive type semiconductor layer (4) second
An injected current with a current amplification factor of 0 times the current amplification factor of the transistor amplifier formed from the conductive semiconductor layer (5) can flow through the active layer (2), and laser oscillation corresponding to the current amplification rate can be caused by the active layer (2).
) A semiconductor laser device characterized by ε obtained from ε.