JPH0210770A - Optical set/reset circuit - Google Patents

Abstract

PURPOSE:To miniaturize it and to stabilize the operation by forming a rare element monolithically on a semiconductor substrate. CONSTITUTION:The collector layer of the first PNP phototransistor 251 and the emitter layer of the second PNP light transistor 261 are contacting with the uppermost anode layer of a PN light emitting diode 27. The elements of transistors 251 and 261 are isolated by an etching groove, and to the emitter layer of the transistor 251 the positive voltage 28, and to the collector layer of the transistor 261 the negative voltage 29 are being applied. When the set light 211 above the threshold level is input, enough positive voltage is applied to the diode 27, which emits the output light 125. Further, when the reset light 212 is input to the transistor 261, the voltage applied to both ends of the diode 27 lowers, and the light 125 stops. To return both transistors 251 and 261 to OFF, the voltage 28 and 29 are made to O at the same time for a short while, By doing it this way, the miniaturization becomes possible, the power consumption becomes small and the operation is stabilized, and the input can also be done with the light of the output.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is an optical output switching circuit, which is one of the most important circuits among the optical logic circuits required to realize optical switching and optical computers. The present invention relates to an optical set/reset circuit that can be turned on and off using light.

(Prior Art) Conventional logic circuits have been made using electronic circuits mainly using transistors. Electronic circuits are expected to continue to develop both now and in the future, but in some areas their limits are beginning to appear. It is a logic circuit in which the number of wires connecting transistors is much larger than the number of transistors. Typical examples include massively parallel processors with an extremely large number of processors, and neurocomputers where all elements are connected and information is stored in the weights of those connections. In an attempt to break through the limitations of wiring in such electronic circuits, attempts have been made to improve the density of wiring using optical wiring and to make the wiring arbitrarily variable. for example,
Liu W. Goodman et al.
an et al.) in the proceedings off the
I.E.E. 1984 Volume 72 No. 85
0 pages (Prodeeding of the IEE
E., vol. 72, 1984) proposed the above-mentioned concept of optical wiring. Although this proposal has not been actually prototyped and is merely a proposed concept, it is an innovative attempt to improve wiring limitations using optical wiring. However, among these proposals, there are almost no proposals regarding optical set-reset circuits that can control the on and off of optical output using light, and none of them are of practical use. Practical means that it can be made smaller like an electronic circuit, consumes less power, and operates stably.

(Objective of the Present Invention) As described above, an object of the present invention is to provide an optical set/reset circuit that can be downsized like an electronic circuit, consumes little power, and operates stably.

(Means for Solving the Problems) According to the first aspect of the present invention, two phototransistors that are switched by incident light are formed on a light emitting diode formed on a semiconductor substrate, and the first the collector layer of the second phototransistor and the emitter layer of the second phototransistor are in contact with the top layer of the light emitting diode;
According to the second aspect of the present invention, two PNP transistors are switched by incident light.
an N-type optical thyristor is formed on a light emitting diode formed on a semiconductor substrate, and the cathode layer of the first optical thyristor and the cathode layer of the second optical thyristor are in contact with the top layer of the light emitting diode, and An optical set/reset circuit is obtained in which the two optical thyristors are element-separated.

(Operation) The operation of the present invention will be briefly explained below using FIG. 2. FIG. 2(a) is an equivalent circuit of an optical set-reset circuit explaining the first aspect of the present invention. The constituent elements are phototransistors 251 and 261 and a light emitting diode 27. Here, PNP phototransistor 251
and 261 are used, and the collector layer of the first PNP phototransistor 251 and the emitter layer of the second PNP phototransistor 261 are in contact with the uppermost anode layer of the PNN all-light emitting diode 2. The two phototransistors are separated by an etched groove. A positive voltage 28 is applied to the emitter layer of the first PNP phototransistor 251, and a positive voltage 28 is applied to the emitter layer of the first PNP phototransistor 251.
A negative voltage 29 is applied to each collector layer through a load resistance. A circuit having such a configuration constitutes the first invention.

Next, the operation of this circuit will be explained. Phototransistor-25
When the set light 211 at a threshold level of 1 or higher is input to the phototransistor 251, this transistor becomes conductive. Then, a positive voltage sufficient for operation is applied to the light emitting diode 27, and output light 125 is emitted. In this state,
When the reset light 212, which is equal to or higher than the threshold level of the phototransistor 261, is input to the phototransistor 261, this transistor becomes conductive. Then, the voltage applied to both ends of the light emitting diode 27 decreases, a positive voltage sufficient for light emission is no longer applied, and the light emission of the output light 125 is stopped.

In order to return both phototransistors to their original off state, the positive voltage 28 and the negative voltage 29 are simultaneously brought to zero for a short period of time.

In this way, an optical set/reset circuit is modified in which the light emitting diode takes on a non-emission state and a light emitting state depending on the incident state of the set light and the reset light.

FIG. 2(b) is an equivalent circuit diagram of an optical set-reset circuit explaining the second aspect of the present invention. The constituent elements are optical thyristors 252 and 262 and a light emitting diode 27. Here, PNPN optical thyristors 252 and 262 are used, and the cathode layer of the first PNPN optical thyristor 252 and the anode layer of the second PNPN optical thyristor 262 are in contact with the uppermost anode layer of the PNN all-light emitting diode 2. . The two optical thyristors are separated by an etched groove. and the first PNPN
A positive voltage 28 is applied to the anode layer of the optical thyristor 252, and the second PNPN optical thyristor 262-
A negative voltage 29 is applied to the hard layer. A circuit having such a configuration constitutes the second invention.

Next, the operation of this circuit will be explained. Optical thyristor-252
The set light 211 at or above the threshold level of the optical thyristor 2
52, this thyristor becomes conductive. Then, a positive voltage sufficient for operation is applied to the light emitting diode 27, and output light 125 is emitted. In this state, when the reset light 212 of a level equal to or higher than the threshold level of the optical thyristor 262 is input to the optical thyristor 261, this thyristor becomes conductive. Then, a sufficient positive voltage is no longer applied to both ends of the light emitting diode 27 for operation, and the output light 1
25 stops emitting light. In order to return to the original state, the positive voltage 28 and negative voltage 29 may be reduced to zero at the same time.

In this way, an optical set/reset circuit is modified in which the light emitting diode takes on a non-emission state and a light emitting state depending on the incident state of the set light and the reset light. In such an optical circuit, the PNPN element has a latch function that maintains its state even if the optical input is cut off, so it is only necessary to apply voltage to the terminal 28 when an output is required, which reduces power consumption. .

(Example) Next, an example of the present invention will be described in detail using the drawings. FIG. 1 is a diagram illustrating details of the first invention.

For the semiconductor substrate 11, an N-type GaAs semiconductor was used.

A ground electrode 10 is formed on the back side of this semiconductor substrate 11. On this semiconductor substrate 11, N-type AlGaA
s cathode layer 121, GaAs light emitting layer 122, P type Al
A GaAs anode layer 123 is formed. Then, high-resistance AlGaAs current blocking layers 15 were formed on both sides of the GaAs light emitting layer 122 so that current flows concentratedly through the GaAs light emitting layer 122, and light emitting diodes 27 that emit light were formed on stripes. The light emitting diode 27 here is a surface emitting type LED without a resonator. A light emitting window 124 for extracting light output 125 is formed in the etched groove. Two phototransistors 251 and 261 were then formed on the light emitting diode. In the left sectional view of FIG. 1, a set PNP optical transistor 251 is formed in the left half, and a reset PNP optical transistor 261 is formed in the right half. The set phototransistor 251 is made of P-type Al
A GaAs collector layer 161, an N-type GaAs base absorption layer 181, a P-type AlGaAs emitter layer 171, and a positive electrode 191 are laminated. The positive electrode 191 has a set light entrance window 20 for allowing the set light 211 to enter.
1. A positive electrode terminal 221 is added. The reset phototransistor 261 includes a P-type AlGaAs emitter layer 172, an N-type GaAs base absorption layer 182, and a P-type A
A lGaAs collector layer 162 and a negative electrode 192 are laminated. The negative electrode 192 includes a set light entrance window 202 for allowing the set light 212 to enter, and a negative electrode terminal 2.
22 is added.

With the above-described structure, the light emitting diode 27 and two phototransistors 251 and 261 shown in FIG. 2(a) were formed on the semiconductor substrate seven times.

When the set light 211 of 0.78 microns is input to the phototransistor 251, this transistor becomes conductive. Then, the light emitting diode 27 receives about 1
．． A positive voltage of 5V is applied and output light 125 with a wavelength of 0.87 microns is emitted. In this state, the phototransistor-2
When the reset light 212 of 0.78 microns is input to 61, this transistor becomes conductive. Then, the voltage applied to both ends of the light emitting diode 27 decreases, a positive voltage sufficient for light emission is no longer applied, and the light emission of the output light 125 is stopped. To return to the original state, the positive voltage 28 and negative voltage 29 are simultaneously brought to zero for a short time.

In this way, an optical set-reset circuit is obtained in which the light-emitting diode takes a non-light-emitting state and a light-emitting state depending on the incident state of the set light and the reset light.

In the embodiments described above, minute elements are monolithically formed on a semiconductor substrate, so they can be miniaturized like electronic circuits, have low power consumption, and can be inputted so that information can be exchanged by light. A light set/reset circuit is obtained whose function is performed by the output light.

FIG. 3 is a diagram illustrating details of the second invention.

In this embodiment, PNPN photothyristors 252 and 262 are used instead of the phototransistor of the first invention, and the cathodes 252 and 262 of this device are in contact with the anode, which is a P-type semiconductor, of a PN light emitting diode. ing. The cathode of the set optical thyristor 252 and the anode 27 of the light emitting diode 27 are connected by wiring so that they are always electrically connected.

Similar to the embodiment of the first invention, an N-type AlGaAs cathode layer 121, a GaAs light emitting layer 122, and a P-type AlGaAs anode layer 123 are formed in this order on a semiconductor substrate 11. Then, high-resistance AlGaAs current blocking layers 15 were formed on both sides of the GaAs light emitting layer 122 so that current flows concentratedly through the GaAs light emitting layer 122, and light emitting diodes 27 that emit light were formed on stripes. Two PNPN photothyristors 252 and 262 were then formed on the light emitting diode. In the left sectional view of FIG. 1, a set PNPN optical thyristor 252 is formed in the left half, and a reset PNPN optical thyristor 262 is formed in the right half. The set optical thyristor 252 includes a P-type AlGaAs anode layer 371, an N
A GaAs-based absorption layer 381, a P-type GaAs-based absorption layer 385, an N-type AlGaAs cathode layer 361, and a positive electrode 391 are stacked. The positive electrode 391 has a set light entrance window 20 for allowing the set light 211 to enter.
1. A positive electrode terminal 221 is added. P for reset
The NPN optical thyristor 262 includes a P-type AlGaAs anode layer 372, an N-type GaAs base absorption layer 382, and a P-type AlGaAs anode layer 372, an N-type GaAs base absorption layer 382, and a
A GaAs-based absorption layer 386, an N-type AlGaAs cathode layer 362, and a negative electrode 392 are stacked. Further, the negative electrode 392 is provided with a set light entrance window 202 for allowing the set light 212 to enter therein, and a negative electrode terminal 222.

With the above-described structure, the light emitting diode 27 and the two optical thyristors 252 and 262 shown in FIG. 2(a) are monolithically formed on the semiconductor substrate.

In this way, an optical set-reset circuit is obtained in which the light-emitting diode takes a non-light-emitting state and a light-emitting state depending on the incident state of the set light and the reset light. In such an optical set/reset circuit, since the PNPN element has a latch function, it is only necessary to apply a voltage to the terminal 28 when an output is required, and power consumption can also be reduced.

In the embodiments described above, minute elements are monolithically formed on a semiconductor substrate, so they can be miniaturized like electronic circuits, consume less power, and can be set and reset with light, and the output is also light. An optical set/reset circuit is obtained having the functions performed in the following.

It is clear that the same effect can be obtained even with a structure having a conductivity type completely opposite to that of the above embodiment.

It is clear that the thickness and composition of each layer described in the above embodiments are not particularly limited.

Although GaAs/GaAlAs-based semiconductors were used in the above embodiments, the present invention is not limited to this material system.
Other compound semiconductors such as InP/InGaAsP are also possible.

In the above embodiment, an LED without a resonator was used as the light emitting diode, but a diode laser having a resonator configuration and capable of producing a laser output may also be used.

(Effects of the Invention) As explained above, according to the present invention, minute elements are monolithically formed on a semiconductor substrate, so it can be miniaturized like an electronic circuit, has low power consumption, and An optical set/reset circuit has been obtained which has the function of inputting and outputting light so that information can be exchanged.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of the light emitting diode used in the embodiment of the first invention, and FIGS. Figure 3 is the second
FIG. 2 is a diagram showing the structure of a PNPN optical thyristor used in an embodiment of the invention. In the figure, 10 , , , , earth electrode, 11 , ,
, , , , N-type GaAs semiconductor substrate, 15
,,,,,,,,. 121 , , , , , . 122 , , , , , . 123 , , , , , . 124 , , , , , . 125 , , , , , . 161.172,,. 171.162,,. 181.182,,. 191 , , , , , . 192 , , , , , . 201 , , , , , . 202 , , , , , . 211 , , , , , . 212 , , , , , . 221 , , , , , . 222 , , , , , . 251 , , , , , . 261 , , , , , . 27 , , , , , , . AlGaAs current blocking layer, N-type AlGaAs cathode layer, GaAs light emitting layer, P-type AlGaAs anode layer, output light window, output light, P-type AlGaAs collector layer, P-type AlGaAs emitter layer, N-type GaAs base absorption layer, positive electrode, Negative electrode, set light incidence window, reset light incidence window, set light, reset light, positive electrode terminal, negative electrode terminal, PNP phototransistor for setting, PNP phototransistor for resetting, PN light emitting diode, 28,,,,,,,,, . 29 , , , , , , . 252 , , , , , . 262 , , , , , . 361.372,,. 362.371,,. 381.386,,. 385.382,,. 391 , , , , , . 392 , , , , , . shows. Positive electrode, negative electrode, PNPN optical thyristor for setting, PNPN optical thyristor for resetting, N-type AlGaAs cathode layer, P-type AlGaAs anode layer, N-type GaAs gate absorption layer, P-type GaAs gate absorption layer, positive electrode, negative electrode,

Claims (2)

[Claims] (1) A light-emitting diode (including a diode laser, hereinafter collectively referred to as a light-emitting diode) in which two optical transistors that are switched by incident light are formed on a semiconductor substrate.
a collector layer of the first phototransistor and an emitter layer of the second phototransistor are in contact with the top layer of the light emitting diode, and the two phototransistors are separated from each other. Set reset circuit. (2) Two PNPN type optical thyristors that are switched by incident light are formed on a light emitting diode formed on a semiconductor substrate, and the cathode layer of the first optical thyristor and the cathode layer of the second optical thyristor are formed on a light emitting diode formed on a semiconductor substrate. is in contact with the top layer of a light emitting diode, and the two optical thyristors are separated into elements.