JPH03216628A - Optical three-terminal element - Google Patents

Abstract

PURPOSE:To provide the optical three-terminal element which is small in element shape, is suitable for arraying, and has a quich motion by successively laminating an optical modulating part which has a pin structure and changes the transmittance of 1st light with an impressed voltage and a phototransistor which has an npn structure and changes output current with the intensity of 2nd light. CONSTITUTION:The optical modulating part 3 which has the pin structure and changes the transmittance of the 1st light with the impressed voltage and the phototransistor 2 which has the npn structure and changes the output current with the intensity of the 2nd light on a semiconductor substrate 4. Since the monolithically constituted element is formed in this way, the shape of the element is extremely small and the high-speed optical gate processing is executed with the simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical three-terminal element that controls the intensity of light with the intensity of another light.

[Prior Art] The development of optical three-terminal devices is highly desired as a key device for optical information processing and optical signal processing. Conventionally, this type of element includes a silicon phototransistor and a pin-type modulator that includes a gallium arsenide multiple quantum well (MQW) structure, as shown in "Electronics Letters Vol. 23, p. 92". A type of device has been proposed that is a hybrid combination of When bias light of a constant intensity is incident on the pin type modulator, the intensity of the transmitted light is controlled by the intensity of the light incident on the phototransistor.

The features of the element having such a configuration are as follows.

■High sensitivity can be obtained due to the amplification effect of the phototransistor.

■High-speed response can be obtained due to the quantum confined Stark effect (QCSE) in the MQW pin structure.

■As it is a passive element, power consumption is low.

- Great flexibility in setting the wavelength of the incident light to the phototransistor and the high-ass light of the pin type modulator.

[Problem to be solved by the invention]

By the way, since the above-mentioned element originally has a structure in which two separate elements are hybrid-coupled, the shape of the element must be large, and there is a problem that it is unsuitable for one-dimensional or two-dimensional array formation. Further, although high-speed response is expected from the operating principle of the element, there are problems in that stray capacitance associated with wiring between elements is large and response speed is low.

The present invention has been made in view of these points, and its purpose is to realize an optical three-terminal device that has a small device shape, is suitable for array formation, and has a high operating speed.

[Means to solve the problem]

In order to achieve such an object, the present invention is No. 1? An optical three-terminal element that controls the intensity of the first light by the intensity of the second light includes, on a semiconductor substrate, a light modulating section having a pin structure and changing the transmittance of the first light according to an applied voltage;
This device has a structure in which pho-transistors whose output current changes depending on the intensity of the second light are sequentially stacked.

[Effect]

The optical three-terminal device according to the present invention can be realized in a monolithic configuration, has an extremely small device shape, can easily be formed into a dimensional or two-dimensional array, and can provide high-speed response.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a connection diagram showing an equivalent circuit of an optical three-terminal device according to the present invention. In the same figure, ■ is a constant voltage power supply with voltage ■8, 2
is a phototransistor, 3 is a pin diode as a light modulation section, 2C is a collector of phototransistor 2, 2
E is the emitter of phototransistor 2, or the input light,
Is L b i■ bi? Suko, L. ■ is transmitted light. The device shown in FIG. 1 has a configuration in which a phototransistor 2 and a pin diode 3 are connected in series, and is operated by connecting a constant voltage power source 1 to both ends thereof. Phototransistor 2 and p
Depending on the connection method of the in diode 3, the emitter-coupled type (
They are classified into the collector-coupled type (FIG. 1(a)) and the collector-coupled type (FIG. 1(a)). The emitter-coupled type is a phototransistor 2
A pin diode 3 is connected to the emitter 2E side. On the other hand, the collector-coupled type has a pin on the collector 2C side.
Diode 3 is connected.

The operating principle of the element having such a configuration will be explained below. The input light (second light) of the phototransistor 2 is input to the L. , pi
The bias light (first light) of the n diode 3 is L b i
m *, its transmitted light is L. u%, bias light L
Let the intensity of b ia * be constant. Lbi. The wavelength of s is determined by the reverse bias voltage V.s. The i-MQw layer 32 (
(see FIG. 2), and the wavelength of Li is set to a wavelength sensitive to the phototransistor.

When the human power light L in is zero, the phototransistor 2 is in an off state, so the voltage applied to the pin diode 3 is zero. At that time, the i-MQW layer 32 is in a transmitting state, and transmitted light L out which is close in intensity to the bias light L bias is obtained. Next, when the input light L in is increased, the phototransistor 2 is turned on, and the voltage applied to the pin diode 3 changes to approximately V. At that time, the i-MQW layer 32 becomes an absorption state due to the quantum confined Stark effect (QCSE), and L 6
The strength of ut decreases rapidly. That is, the input light L. Transmitted light L by n. at can be switched. Since a phototransistor usually has a current amplification factor of about 100, the strength of L1fi required for switching is L
It is about 1/100 of out.

FIG. 2 shows an embodiment of the optical three-terminal device according to the first invention (the invention set forth in claim 1) of the present invention, and FIG. FIG. 3 shows an embodiment of the optical three-terminal element according to the third invention (Claim 3) of the present invention.
Embodiment of the optical three-terminal device according to the described invention), FIG.
) shows an example of an optical three-terminal device according to the fourth invention (invention according to claim 4).

In FIG. 2, an NPN phototransistor 2 is stacked on a PIN diode 3. The collector-coupled type is shown in the figure (al), and the emitter-coupled type is shown in the top of the figure. In the case of collector-coupled type, the pin diode p
n to electrically short-circuit the layer 3l and the n-type collector layer 23.
A "p" tunnel junction 5 is formed. This junction 5 also serves to completely absorb the light L in input to the phototransistor 2 and prevent it from reaching the pin diode 3 . In the case of the emitter-coupled type, an n-type spacer layer 5a is inserted instead of the tunnel junction, and the n-layer 33 of the pin diode and the n-type emitter layer 21
is electrically shorted. In the elements having these structures, Lin is incident from the front surface side, and bias light Lio is incident from the substrate 4 side, and output light L is generated. ut is extracted as transmitted light or reflected light. In addition, in the case of a reflective type optical three-terminal device as an embodiment of the fifth invention (invention according to claim 5), the p on the surface side of the pin diode 3
The layer or n-layer is composed of a multilayer film reflecting mirror 6 having a structure in which two semiconductor layers having different refractive indexes are repeatedly laminated. In addition, in FIG. 2, 22 is a p-type base layer.

FIG. 3 shows an npn phototransistor 2, contrary to FIG.
A PIN diode 3 is formed on top of the pin diode 3 . In this case as well, in the collector-coupled type, the phototransistor 2 and the pin diode 3 are connected by the tunnel junction 5. L1,l is incident from the substrate 4 side. On the other hand, L
The via* is incident from the front side, and the output light L out is extracted as transmitted light or reflected light.

The above structure is achieved by using an element configuration as shown in the table, which is lattice matched to, for example, a GaAs substrate or an InP substrate. Lb
The wavelength band of ias is also shown. In addition, in the table, HB
T indicates a heterojunction bibolar transistor.

? FIG. 4 is a cross-sectional view showing a specific example, in which on a GaAs substrate 4,
GaAs/Alo. xGao. tAsMQWpin diode 3, GaAs tunnel junction 5, and GaAs
/A 16. sG ao. 2 is a cross-sectional view of an element having a structure in which tA s HBT 2 is sequentially stacked. n-Aj in HBT2! o. sGao. An n-GaAs camp layer 20 is stacked on top of the tAs emitter layer 21, and an ohmic electrode 7 is further formed on top of the n-GaAs camp layer 20. Group F
Another ohmink electrode 7 is formed on the back surface of i4. The p layer of the pin diode is A 1 61G
a6. It is a multilayer film reflecting mirror structure 6 in which qA S layers and AIAs layers are alternately and repeatedly laminated, and bias light L■ is incident from the substrate 4 side. reflect. Note that the input light L i
l1 is incident from the front side.

The size of the element is 100I! It has a diameter of m.

FIG. 5 is an equivalent circuit diagram for explaining the optical three-terminal device according to the present invention. FIG. 6 also shows L. ．． ，? bia
The wavelength of L.s is 850 nm, the intensity of Lbims is 1 mW, and the wavelength of L.s is 850 nm. The I-VIV2 curves of the HBT 2 and the pin diode 3 are shown superimposed on the same coordinate axis when , , is changed from O to 10 μW. The voltage V of the constant voltage source l (FIG. 1) is 5V. The definitions of the current I, the voltage applied to the phototransistor V1pin, and the voltage applied to the diode 2 are as shown in FIG. L. ,, is 0μ
When W is increased by 1μW, 2μW, 3μW, etc., the operating points of the pin diode are A, B, C.
, D,..., and the applied voltage of pin diode 3 is
2 is built-in voltage 1■, reverse bias voltage -
The voltage suddenly changes to 3.5V.

FIG. 7 is a graph showing the L in vs. L out characteristics of this element (the conditions of Lb, ■ and ■8 are the same as in FIG. 6). As L in increases from 0 to 3 μW, L out changes rapidly from 600 μW to 3 oo μW, and a clear negative logic optical three-terminal characteristic appears.

〔Effect of the invention〕

As explained above, the first aspect of the present invention includes, on a semiconductor substrate, a light modulating section having a pin structure and changing the transmittance of the first light according to an applied voltage, and a light modulating section having an npn structure and having a 2
By sequentially stacking phototransistors whose output current changes depending on the intensity of light, it is possible to provide an element with a monolithic structure, so the element size is extremely small and high-speed optical gate processing can be performed with a simple configuration. effective. Furthermore, since it can be easily formed into a one-dimensional or two-dimensional array, it has the effect of enabling large-scale parallel processing.

Further, the second aspect of the present invention is a light modulation section having a pin structure on the semiconductor substrate and changing the transmittance of the first light depending on an applied voltage, and a light modulation section having a p"+n" structure and having a light modulation section. a tunnel junction connecting the phototransistor and the npn
structure, and the output current changes depending on the intensity of the second light.
In addition to the effects of the invention described above, there is an effect of preventing input light from reaching the optical modulation section.

Furthermore, the third invention of the present invention is provided with a phototransistor having an npn structure on a semiconductor substrate, the output current of which changes depending on the intensity of the second light, and a phototransistor having a pin structure, which changes the output current depending on the applied voltage. The same effects as the first invention can be obtained by sequentially stacking the light modulating part that changes the transmittance of the light modulating part.

Furthermore, a fourth invention of the present invention provides a phototransistor having an npn structure on a semiconductor substrate and changing the output current depending on the intensity of the second light, and a phototransistor having a p + n + − structure. The effect of the third invention is achieved by sequentially stacking the tunnel junction that connects the light modulator and the light modulator, and the light modulator that has a pin structure and changes the transmittance of the first light depending on the applied voltage. In addition, it has the effect of preventing input light from reaching the optical modulation section.

Furthermore, the fifth aspect of the present invention is the first, second, third or fourth aspect of the present invention.
In the invention of p.
By including it in the p-layer or n-layer of the in-structure, reflected light can be obtained as output light.

[Brief explanation of drawings]

FIG. 1 is a connection diagram showing an equivalent circuit for explaining an embodiment of the optical three-terminal device according to the present invention, and FIGS. 2 and 3 illustrate embodiments of the first to fifth inventions of the present invention. Fig. 4 is a sectional view showing a specific example of Fig. 2 f8).
The figure is an equivalent circuit diagram for explaining the optical three-terminal device according to the present invention, FIG. 6 is a graph showing the IV characteristics in the circuit of FIG. 5, and FIG. 7 is a graph showing the output light versus input light characteristics. be. 1... Constant voltage power supply, 2... Phototransistor, 3
... pin diode, 4 ... substrate, 5 ... tunnel junction, 5a ... spacer layer, 6 ... multilayer film reflector, 7 ... Ohmifuku electrode, 20 ... camp layer
21... N-type emitter layer, 22... P-type base layer,
23... n-type collector layer, 3 1-p layer, 3 2 ・
...i-MQW layer, 33...n layer.

Claims (5)

[Claims] (1) In an optical three-terminal element that controls the intensity of the first light by the intensity of the second light, the light has a pin structure on the semiconductor substrate and changes the transmittance of the first light depending on the applied voltage. An optical three-terminal device characterized in that a modulation section and a phototransistor having an npn structure and whose output current changes depending on the intensity of the second light are laminated in this order. (2) In an optical three-terminal element that controls the intensity of the first light by the intensity of the second light, the light has a pin structure on the semiconductor substrate and changes the transmittance of the first light depending on the applied voltage. It has a modulation section, a p^+^+n^+^+ structure, a tunnel junction section that connects the optical modulation section and the phototransistor described later, and an npn structure, and the output current is changed depending on the intensity of the second light. An optical three-terminal device characterized by sequentially stacking phototransistors whose values change. (3) In an optical three-terminal element in which the intensity of the first light is controlled by the intensity of the second light, a phototransistor having an npn structure on a semiconductor substrate and whose output current changes depending on the intensity of the second light. 1. An optical three-terminal device comprising: and a light modulating section having a pin structure and changing the transmittance of the first light according to an applied voltage. (4) In an optical three-terminal element that controls the intensity of the first light by the intensity of the second light, a phototransistor having an npn structure on the semiconductor substrate and changing the output current depending on the intensity of the second light. and has a p^+^+n^+^+ structure,
A light source characterized in that a tunnel junction connecting the phototransistor and the light modulation section described below and a light modulation section having a pin structure and changing the transmittance of the first light according to an applied voltage are laminated in this order. Three terminal element. (5) In the optical three-terminal device according to claim 1, 2, 3, or 4, the multilayer film reflecting mirror structure consisting of a structure in which two semiconductor layers having different refractive indexes are alternately and repeatedly stacked is a p layer of a pin structure or an n layer. 1. An optical three-terminal element comprising: