JPS61239687A - Semiconductor light-emitting element - Google Patents

Abstract

PURPOSE:To give an inverter function to beams by forming two base electrode layers supplying a base layer with currents, applying proper bias voltage to these base electrodes and making carriers to transit in the base layer. CONSTITUTION:An emitter layer 104 and a collector layer 102 form a double- hetero-junction bipolar transistor while holding a base layer 103. Two base electrode layers 105 are each supplied with base currents IB1, IB2. When currents IB1 are fed to a first base electrode 107 from the first bias voltage VB1 only on one side in the layer 103 in the element, laser oscillation 114 is generated. The second bias voltage VB2 is applied to a second base electrode 108, but base currents IB2 by the application of voltage VB2 are brought to the state in which base currents IB2 are made smaller than a laser oscillation threshold. When laser beams 112 are injected selectively to a waveguide on the electrode 108 side under the state, laser oscillation 113 is generated. Oscillation 114 on the electrode 107 side is stopped at that time. Oscillation 108 is generated only during a time when laser beams 112 are injected, and inversion operation is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor light emitting device, and is particularly applicable to the field of optical information processing.

Conventional technology In the research and development of semiconductor laser diodes, which are semiconductor light emitting devices, we have focused on improving device characteristics in the optical communications and optical information processing fields, with themes such as dynamic single mode, frequency chirping suppression, low noise, and high output. Improvements are being made actively.

In response to these demands, many types of semiconductor lasers have been announced in terms of structure and materials.

Light from a semiconductor laser diode is emitted from a semiconductor layer called an active layer, which has a high refractive index and a high gain, by current injection. In the semiconductor laser diode 3 base node, carrier pumping for laser oscillation is performed by current injection into the PN junction. The injection current value that starts laser oscillation is called a threshold current Ith.

When laser light is injected into the active layer of a semiconductor laser diode, carriers undergo population inversion due to optical bombing, so that the threshold current Ith can be lowered, and at the same time, the terminal voltage is reduced.

This phenomenon has been announced by Mitsuhashi et al. of the Electronics Technology Research Institute (IEICE, Optical and Quantum Electronics Study Group Material 0QE80-83). It has been proposed to utilize this phenomenon to both emit and detect light.

Problems to be Solved by the Invention In the present invention, when laser light is injected into the active layer of a semiconductor laser diode, the threshold current Ith decreases;
60 is used in a bipolar transistor for laser oscillation (Japanese Patent Application No. 73380/1983), which has already been filed by the present inventors, to provide an optical switch function.

Ways to solve the problem Wide gap emitter and wide gear knob
Two base electrode layers are formed to supply current laterally to the base layer of a heterojunction bipolar transistor having a collector. The base current is independently supplied to the left and right ends of the base layer from the two base electrode layers. One base current is set to a current value that causes laser oscillation, and the other base current is set to a current value lower than the threshold current value. Laser light is emitted from one of the base layers and not from the other. When laser light is externally injected into the end portion of the base layer from which laser light is not emitted, the threshold current value decreases, causing laser oscillation. As a result, the carriers at the end of the base layer, which were originally lasing, are sucked into the other side and stop lasing. This phenomenon is applied to the optical switch function.

Function: The wide gap emitter and the wide degree gap collector have the function of effectively confining carriers and light within the base layer, which has a smaller pan 6 spaced gap than the emitter and collector. The optical resonator formed in the base layer or the semiconductor layer in contact with the base layer is a mirror for reflecting light confined within the base layer, thereby causing laser oscillation. The bias voltage to the base layer is for supplying the current necessary for laser oscillation. In addition, external laser light injection has the effect of lowering the threshold current value by optical pumping.

Embodiment FIG. 1 shows a semiconductor light emitting device in one embodiment of the present invention. 101 is an n-type InP substrate, 102 is a collector layer formed of an n-type InP epitaxial layer with a lower impurity concentration than the n-type InP substrate 101, and 103 is a p-type InGa
104 is an emitter layer formed from an n-type 1nP epitaxial layer; 104 is an emitter layer formed from a 1nP epitaxial layer;
o5 is a base electrode layer formed of a p-type InP epitaxial layer having an impurity concentration higher than that of the collector layer 102 and emitter layer 104, 106 is a collector electrode made of MuU and an, etc., and 107 and 108 are MuU and Zn, etc. 109 is an emitter electrode made of MuU and Sn, 110 and 111 are first and second bias voltages, 112 is a laser beam selectively injected into the base layer 103 from the outside, 113 and 114 both have different light emitting positions. The second laser beam 116 indicates an insulating film.

Next, the manufacturing process of the semiconductor light emitting device of this example will be explained. An n-type InP layer 102 is formed on an n-type InP substrate 101.
and p-type InGaAsP layer 103 and n-type InP layer 10
4 are sequentially formed by a crystal growth technique such as a liquid phase growth method. After that, using photolithography technology, n
A type 1nP layer 102, a p-type InGaAgP layer 103, and an n-type InP layer 104 are formed on an n-type InP substrate 101 in a convex shape and in a band shape. For etching, hydrochloric acid, bromine, etc.
Formed using methanol etc. Thereafter, the side surfaces are filled with a p-type InP layer 106 with an insulating film etc. placed on the top of the strip. Insulating film 116 is selected for electrode wiring.
□ Selectively open holes to use mu/8n, mu/Zn7, < as electrode metals.

etc. to form the collector, emitter, and base electrodes.

The structure of the device according to the present invention is that the emitter layer 104 and the collector layer 102 have a smaller hand gap than the base layer 103.
This is an npn type double heterojunction bipolar transistor in which a base layer 103 is sandwiched between high energy materials to form a so-called double heterojunction. In FIG. 1, a mirror surface is formed by a cleavage method or the like on a plane perpendicular to the laser beam in order to oscillate the laser beam. The base electrode layer 106 is a so-called graft base, and has a base current IB+ applied to the base layer 103.
, In2 is efficiently supplied.

In the optical configuration of the device of this example, the base layer 103 acts as a light waveguide. The waveguide (base layer) 103 is sandwiched between materials having a low refractive index in the vertical and horizontal directions. As a result, light is confined within the waveguide. Furthermore, light is confined in the lateral direction of the waveguide due to the gain difference caused by current injection.

As described above, the base layer 103 operates as a waveguide that confines light due to the difference in refractive index, and also functions to confine electrons due to the double heterostructure.

In this example element, if the base current rB is supplied to only one side of the waveguide layer (base layer), the laser beam is emitted by recombination of electrons injected into the base layer from the emitter and holes in the base layer. This produces an oscillation 114. The gain of this waveguide is greatest at the position where holes and electrons are supplied. Therefore, the first base pole 10 which is oscillating the laser
The gain of the waveguide on the 7 side is large, and the gain of the waveguide on the second base electrode 108 side is small. Thus, a feature of the present device is that the gain distributions are different within the same waveguide layer.

A second bias voltage vB2 is applied to the second base electrode 108, but the resulting base current IB2 is smaller than the laser oscillation threshold Ith by ΔI. ΔI is very small, and 2 is a value close to causing laser oscillation.

In this state, when laser light 112 is selectively injected from the outside into the waveguide layer 9 on the second base electrode 108 side, holes and electrons are locally generated, and the laser beams are recombined, causing laser oscillation. 113 results. At this time, the number of holes and electrons is destroyed by the hole burning effect, so the holes and electrons existing in the waveguide on the first base electrode 107 side are supplied to the waveguide on the second base electrode 108 side. Ru. As a result, the first base electrode 1 which was initially emitting laser oscillation 114
V-za oscillation in the waveguide on the 07 side stops. Then, only while the laser source 112 is injected from the outside, laser oscillation 113 is generated within the waveguide on the second base electrode 108 side.

FIG. 2 shows a second embodiment of the invention. In FIG. 2, the same numbers as in FIG. 1 indicate the same components as in FIG. Reference numeral 201 indicates an n-type InP layer separating the base layer 103 and the waveguide layer 202. A waveguide layer 202 is formed selectively with respect to the base layer 103 and is optically coupled to the base layer 103. Injection of light from the outside or extraction of light to the outside is performed by the waveguide 202.

In the examples, an InP/InGaAsP system was used, but similar effects can be obtained using a GaAs/GaAaAs system.

Effects of the Invention As described above, according to the present invention, an optical inverter (
It has the effect of having an inversion) effect. That is, the first
Laser oscillation (114 in the example) from the waveguide layer on the side of the base electrode (107 in the example) is output. If the oscillation of the laser beam corresponds to "1" and the stop corresponds to "0'," the input becomes "0" and the output becomes "1", and the input becomes "1" and the output becomes "O". This shows an inverter effect caused by light. A conventional optical inverter is an electrical circuit that combines a light receiving element and a light emitting element. As a result, the conventional Hikari Inno Kuichiyo suffered from an electrical speed delay. The inverter function of the device according to the present invention provides a new semiconductor light emitting device having an inverter function for light as a single functional integrated device rather than a conventional circuit, and is industrially valuable.

11 Be-7・

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a semiconductor light emitting device according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of another embodiment of the present invention. 101... Semiconductor substrate, 102... Collector layer, 103... Base (waveguide) layer, 1
04... Emitter layer, 105... Base electrode layer, 106... Collector electrode, 1o7.
...First base electrode, 108...Second base electrode, 109...Emitter electrode, 11o.
...First bias voltage, 111...Second
Bias voltage, 112... Injection laser light, 11
3...second laser beam, 114...second
Laser light, 116...Insulating film. Name of agent: Patent attorney Toshio Nakao and one other person

Claims (2)

[Claims] (1) An optical resonant device is provided in the base layer of a heterojunction bipolar transistor using a wide gap emitter and a wide gap collector, or a semiconductor layer in contact with the base layer, and at least 1, second, comprising two base electrode layers, applying a first bias voltage that causes laser oscillation to the first base electrode layer with respect to the emitter layer of the transistor; A second bias voltage that does not cause laser oscillation is applied to the first bias voltage that does not cause laser oscillation, and laser light is selectively injected from the outside into the base layer that is in contact with the second base electrode layer. 1. A semiconductor light emitting device characterized in that the light emitted in the base layer in contact with the base electrode layer is transferred to the base layer in contact with the second base electrode layer. (2) To inject laser light into the base layer from the outside,
The semiconductor light emitting device according to claim 1, characterized in that an optical waveguide layer is selectively provided on the base layer.