JPS58134483A - Light emitting photodetector - Google Patents

Abstract

PURPOSE:To obtain a low application voltage element by reducing the energy gaps of emitter, base and collector in this sequence when an N-P-N type phototransistor having an emitter layer, a base layer and a collector layer from upper layer is formed on a semiconductor substrate, and setting the emitter to a negative voltage, the base to a positive voltage at the light emitting time, and the emitter to the negative voltage and the collector to the positive voltage at the light receiving time. CONSTITUTION:An N<-> type GaAS layer 2 to become an emitter of an N-P-N type phototransistor, a P type Ga0.95Al0.05As layer 3 to become a base and an N type Ga0.65Al0.34As layer 4 to become a collector are sequentially laminated on an n<+> type GaAs substrate 1. In this configuration, the energy gap of the respective layers are set to the relationship of the layer 4 the layer 3 the layer 2. Thereafter, a collector electrode 5 is mounted on the back surface of the substrate 1, a base electrode 6 is mounted on the layer 3, and an emitter electrode 7 is mounted on the layer 4, the polarities of the voltages to be applied to the electrodes are selected and light is emitted and received.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a nine-light-emitting and light-receiving element having both light-emitting and light-receiving functions, which is used for bidirectional optical transmission through a single optical fiber.

In the practical application of optical fiber overconfidence, there are great expectations for light-emitting and light-receiving devices that enable bidirectional optical transmission using a single optical fiber as a means of realizing a simple, low-cost V-stem.

One way to realize a light-emitting and light-receiving device is to use a conventional light-emitting diode (LID), which is forward biased when emitting light and reverse biased when receiving light, and used as an abawon photodiode (PD). There are 6 and 9 things that are established and receive light.

Although the structure of No. 4 is simple, it has the disadvantage that it requires rounding to be used as a mu PD when receiving light, requires a high applied voltage, and generates large noise. (9) When emitting and receiving light with the same p-n welding, comparing the emission wavelength spectrum and the light-receiving sensitivity spectrum, we find that the light-emitting wavelength spectrum μ is the light-receiving sensitivity spectrum). This means that only a part of the long region has light-receiving sensitivity.

The object of the invention is to obtain a light-emitting light-receiving element that has a simple structure, can be driven with low noise, low applied voltage, and has high light-receiving sensitivity.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a sectional view showing an example of a light emitting light receiving element according to the present invention.

In the same figure, l is an n-GIAS substrate, and this substrate l
On the main surface of
．． 96 Mlo, Obm 11 and 11 Glo, eaA
The lo, siA@ layers 4 are sequentially formed in a stacked manner. These were formed by liquid phase epitaxial method and have thicknesses of 3 μm, 1 μm, and 4 μm, respectively. This one is the above n −G a O,・aAlo, s6
An npn-type "7" transistor is constructed by tossing the emitter, base, and collector of the emitter, base, and collector of the emitter, base, and collector layers, respectively. It is set to have the following relationship: energy gap>base 1 energy gap>collector's energy gap.

S is a collector electrode made of Mu-Ge, 6 companies Mu-U-Zn
The base electrode, consisting of ? This is an emitter electrode made of U-Ge.

In the above configuration, the light emission mode will be explained with reference to FIG. Power supply IC, emitter voltage! 1i7KjlL, when a positive voltage is applied to the base electrode 6, it works as a single heterojunction light emitting diode. The operation will be explained as follows with reference to the energy band diagram shown in FIG. When a forward bias is applied to the above junction, n-Ga0.・
Violence l・、■MuS layer 4 side P-GlG, 9 easymu Jo,
os1mus @ Electron injection occurs to the B side, and when this electron recombines with hope p, this G...
Light with a wavelength of 830 nm, which corresponds to an energy gap of $1,000, is emitted.

On the other hand, the photodetector will be explained with reference to FIG. Power IC.

When a negative voltage is applied to the collector electrode 7 and a positive voltage is applied to the collector electrode 1K, this acts as a phototransistor.

The operation will be explained as follows with reference to the energy band diagram shown in FIG. When light hits the phototransistor, the emitter (g) and base j-
The light that has passed through is absorbed by the collector depletion layer, 1':,1, and is converted into a light stream. At this time, the wavelength sensitivity of this phototransistor is 7, which corresponds to the energy gap of the emitter and the energy gap of the collector.
00 nm to g 7 Q nm.

In Figure 6, the emission wavelength spectrum of this device is shown by curve 1.
The light receiving sensitivity spectrum is also shown as a curve.

As is clear from FIG. 6, in the above configuration, the light receiving wavelength spectrum A/b can cover the entire emission spectrum, and the light receiving property is greatly improved.

In the above example, the explanation was made using a G51AJ mu$ system element, but
Instead of this, for example, 工n()li! ! This can also be applied to the I' system.

Oku, when receiving light, I used base 1 in the open state, but if you connect it, you can use it at high speed.

According to this invention, it is possible to have both light emitting and light receiving functions with a simple structure of three layers of n-p-n.
It has a rounded light-receiving sensitivity spectrum that covers the entire emission wavelength spectrum, has high efficiency, and has a large photocurrent due to the amplification effect of the transistor. Furthermore, the applied voltage is as small as several points A/), and there is an advantage that there is little noise.

[Brief explanation of the drawing]

FIG. 1 is a device cross-sectional view showing an example of a light-emitting light-receiving device according to the present invention, FIGS. 2 and 3 are connection diagrams and energy band diagrams showing the light emission mode of the device in FIG. FIG. 5 is a connection diagram and energy band diagram showing the light reception mode, respectively, and FIG. 6 is a characteristic diagram showing the light emission wavelength spectrum μ and light reception sensitivity spectrum of the device in FIG. 1. l...Semiconductor substrate, 2...Collector layer, 1...Base layer, 4...Emitter layer, 5...Collector electrode, 6...Base electrode st, y...Emitter electrode . Patent applicant: Tateishi Electric Co., Ltd. Figure 1 Figure 2 Figure 3 n P:K::,. Figure 4 Figure 5 η Pn Figure 6':, A

Claims (1)

[Claims] (1) comprising a semiconductor substrate and a nine-MPN type photon ν star formed in layers on the semiconductor substrate;
, the gap is set smaller as the gap goes further in the order of nicks, and when emitting light, a negative voltage is applied to the emitter and a positive voltage is applied to the base, and when receiving light, a negative voltage is applied to the emitter and a positive voltage is applied to the collector. It consists of nine light-emitting light-receiving elements.