JPS6041262A - Semiconductor device - Google Patents

Abstract

PURPOSE:To increase the storing time and to enhance the integrating density by controlling the flow rate of secondary electrons formed in a hetero junction multilayer film by the space charge amount of the electrons collected to an electron trap and the light emitting effect. CONSTITUTION:In a semiconductor having a semi-insulating GaAs substrate 11, non impurity-added GaAs layer 12, 16, impurity-added AlGaAs layers 13, 15, Si-high density N type AlGaAs layer 14, a voltage is applied between a source electrode 17 and a drain electrode 18, hot electrons in a channel 19 are applied into the layer 14, collected to the high density electron trap to high resistance state. After the voltage between the source and the drain is set to zero for several minutes, the voltage is again applied. Then, it becomes high resistance state. When a light is emitted in this state, the electrons collected to the trap are flowed to the channel 19, becoming low resistance state, thereby maintaining the low resistance state even if the light emission is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor device in which the flow rate of high-mobility electrons distributed in a two-dimensional state is controlled by light.

(Prior Art) FIG. 1 shows a structural diagram of a conventional semiconductor device in which the flow rate of conduction electrons is controlled by light. In Fig. 1, 1 is a p-type Si emitter doped with B (boron), and 2 is an As (
3 is a p-type Si collector doped with B.

By irradiating the vicinity of the emitter-base junction with light, shim-hole pairs are formed, minority carriers are injected into the base region, and a collector current approximately proportional to the amount of light irradiation flows. FIG. 2 shows changes in the electrical characteristics of the semiconductor device shown in FIG. 1 with respect to the amount of light irradiation. The current/voltage characteristics are pentode characteristics, and a collector current proportional to the amount of light irradiation flows. Therefore, in this semiconductor device, since the collector current changes at the same time as the amount of light irradiation changes, there is no memory function regarding the amount of light irradiated in the past. Furthermore, it is difficult to integrate a large number of semiconductor devices having such a structure on one substrate, and it is difficult to apply them to a Zollena type integrated circuit.

(Purpose of the invention) The purpose of this invention is to overcome these drawbacks.

It is possible to control the amount of space charge accumulated according to the amount of light irradiation,
It is an object of the present invention to provide a semiconductor device having a memory function of the presence or absence of past light irradiation.

(Structure of the Invention) In order to achieve the above object, the present invention provides an n or n thousand-handed conductor layer with a large electron trap density and a relatively low electron affinity; creates a heterojunction structure with a relatively large semiconductor layer, and creates a channel layer by accumulating two-dimensional electrons at the heterojunction interface on the side of the semiconductor layer that has a relatively large electron affinity. By injecting conduction electrons into a small semiconductor layer and trapping them in an electron trap, a negative space charge region is formed to make the channel layer highly resistive, and the trapped electrons are released by irradiation with light. In this embodiment, two-dimensional electrons are accumulated in the channel layer to lower the resistance. Examples will be described below.

(Embodiment) FIG. 3 shows a first embodiment of the present invention, in which 11 is a semi-insulating GaAs substrate, 12 is an impurity-free GaAs layer with a thickness of about 1000X, and 13 is an impurity-free GaAs layer with a thickness of about 1000X. AAo, 3Gaq, 7AS layer with thickness of , 14 is N-A70+3Ga0 with thickness of about 500X with high concentration of 81 doped.
7As layer, 15 is Aj with a thickness of about 60X without addition of impurities
? 0.3 Gao7AS layer, 16 is αaAs with no impurity added
Layers 17 and 18 are Au-Ge/N embedded in holes drilled in GaAs layer 16 with a spacing of approximately 10 μm.
These are the source and drain electrodes of the i/Au ohmic junction. Reference numeral 19 denotes a channel made of two-dimensional electron gas accumulated near the junction interface of the GaAs layer 16. To operate this, the semiconductor device is cooled to about 77°, a voltage of approximately 5 cm is applied between the source electrode 17 and the drain electrode 18, and electrons (hot electrons) with large kinetic energy are generated in the channel 19. ), and the hot electrons are transferred to the Si-added A/o, 3Gao, 7AS layer 1.
By injecting electrons into the channel 19 and trapping them in high-density electron traps to form a large number of negative space charges and depleting the channel 19, a high resistance state can be achieved as shown in FIG.

In this state, when the voltage applied between the source electrode 17 and the drain electrode 18 is set to Ov for several minutes and a voltage of 1 V is applied again, a high resistance state almost equal to the previous state is reproduced. When light is irradiated with a voltage of about 1 V applied, electrons captured by electron traps in the St-doped A10,3Ga (17As layer 14) receive energy from the light and flow into the channel 19, resulting in a low resistance state. In the resistance state, the voltage between the source electrode 17 and the drain electrode 18 is as low as 1V, so the kinetic energy of the electrons in the channel 19 is low, and electrons are not injected from the channel 19 into other layers, which prevents light irradiation. maintains a low resistance state even if the
It can be realized by changing the combination of a o, 7A a, -
For example, instead of GaAs/klO, 5Gao, 7As, Gao, 47Ino, 53A s/A
104a "052"' etc.

(5) As explained above, in the first embodiment, GaAs and AA
o, 3Ga (1,7AS) heterojunction multilayer film with high mobility in the channel 19,
St-doped Alo containing a high concentration of electron traps. 3 Gao
. The electrical conductivity of the channel 19 can be changed by emitting electrons injected or captured into the 7AS layer 14 by irradiation with light. Once an electron is captured, it has an extremely long lifetime of several minutes or more, so it can be used as a memory element with a lifetime of several minutes or more. Further, since this semiconductor device can be easily manufactured in a planar structure in large numbers on one substrate, it has the advantage that it can be easily applied to integrated circuits.

Although the first embodiment was a semiconductor device consisting of two ohmic electrodes, a source and a drain, FIG. 3 shows a semiconductor device of a second embodiment consisting of three ohmic electrodes. 16 and 19 are equivalent to those shown in FIG. 21 to 23 are Au-G layers embedded in holes made in the GaAs layer 16 and spaced apart from each other by about 10 μm.
It is an e/Ni/Au ohmic (6) electrode. In the first embodiment, in order to maintain the memory function, it was necessary to change the source-drain voltage at the same time as the light irradiation, but in the second embodiment, the semiconductor device was cooled to 77°K and the electrodes were cooled to 77°K. By applying a constant voltage of about 6 V to 21 and grounding electrode 23, when the side of A is irradiated with light, the resistance value between electrodes 21 and 22 decreases greatly, and the potential of electrode 22 increases. On the other hand, when light is irradiated to the side of B, the resistance value between electrodes 22 and 23 decreases greatly,
The potential of the light decreases, and it becomes possible to detect which side of A or B is irradiated with light and to store it in memory for a long time, such as several minutes or more. When A is irradiated with light and then B is irradiated with light, the potential shown on the electrode 22 indicates the potential when B is irradiated with light, and A and B constitute a two-point light input flip-flop circuit. There is. In the second embodiment, the number of ohmic electrodes was three, but the same effect can be expected with four or more. Also, in this embodiment, GaAs/AA is used as in the first embodiment.
o, 3 Gao7As combination is GaO,7In
O,53As /AA'0.48 In0,52 AS
etc.

(7) Figure 1 Figure 2 (Effects of the Invention) This invention calculates the flow rate of two-dimensional electrons formed in a heterojunction multilayer film by the amount of space charge of electrons captured in an electron trap and the effect of light irradiation. This method has the advantage of long storage time, and can be used for flip-flop circuits or arithmetic circuits of optical integrated circuits, since it can be highly integrated.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a conventional phototransistor, FIG. 2 is an explanatory diagram of the light irradiation effect of its electrical characteristics, FIG. 3 is a structural diagram of a photo-effect semiconductor device according to an embodiment of the present invention, and FIG. 4 is an explanatory diagram of the light irradiation effect on the electrical characteristics, and FIG. 5 is an explanatory diagram of another embodiment of the present invention. 11-...Semi-insulating GaAs substrate, l 2- GaAs
Layer, 13”・A7o, 3Gao, 7A8 layer, 74-8
i-doped Alo, 3Ga007As layer, 1 s...
A11.3G & [], zAS layer, 16- GaAs layer, 17... source electrode, 18... drain electrode, 1
9...channel, 21-23...ohmic electrode. (8) Figure 3 V Iso V Sword L (V Figure 5 Procedural Amendment (Moromi) 16., 188.1 So 1B Director General of the Patent Office 1, Indication of the Case 1982 Patent Application No. 148746 2 Title of the invention Semiconductor device 3 Relationship with the case of the person making the amendment Patent applicant's office (105) 1-7-12 Toranomon, Minato-ku, Tokyo
Name (029) 'A Chuo Electric Industry I Main Type Company Representative
Director and President Nankai Hashimoto 4, Agent address (105) 1-7-12 Toranomon, Minato-ku, Tokyo
No. 334-

Claims (1)

[Claims] A heterojunction structure is created between an n or 1 semiconductor layer with a large electron trap density and a relatively small electron affinity, and a semiconductor layer with a small electron trap density and a sufficiently low impurity density and a relatively large electron affinity. By accumulating two-dimensional electrons at the heterojunction interface on the semiconductor layer side where the electron affinity is relatively large to create a channel layer, conduction electrons are injected into the semiconductor layer where the electron affinity is relatively small and captured by electron traps. The channel layer is made to have a high resistance by forming a negative space charge region, and the captured electrons are released by irradiation with light to accumulate two-dimensional electrons in the channel layer, thereby lowering the resistance. A semiconductor device characterized by: