JPH03148183A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To form a quantum level of a carrier by a simple structure by realizing nonlinear conduction characteristic by resonance tunnel effect of quantized two-dimensional carrier which is formed at an interface between two semiconductor substrates and a thin film insulating layer. CONSTITUTION:A triangular potential well is formed at an interface between semiconductor substrates 2, 4 and a thin film insulating layer 6 by an SIS (semiconductor-insulator-semiconductor) structure which means that a thin film insulating layer is held between two semiconductor substrates. Quantum levels of two-dimensional carrier formed in the triangular potential well at the both sides holding the thin film insulating layer 6 between are relatively changed by using that a two-dimensional carrier stored in a triangular potential well is quantized. Nonlinear current-voltage characteristic is realized by making a large resonance tunnel current flow only when either of quantum levels at both sides coincides. Thereby, a quantum level of a carrier can be formed by a simple structure.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a semiconductor device and a method for manufacturing the same, and particularly to a nonlinear conduction quantum device having a 5IS (semiconductor-insulator-semiconductor>m structure) and a method for manufacturing the same, in which carriers can be produced with an extremely simple structure. The purpose of the present invention is to provide a semiconductor device in which a quantum level is formed and which has nonlinear conduction characteristics that can be easily manufactured. The device is configured to have nonlinear conduction characteristics due to a resonant tunneling effect of quantized two-dimensional carriers formed at the interface between the two semiconductor substrates and the thin film insulating layer.

[Industrial Application Field] The present invention relates to a semiconductor device and a method for manufacturing the same, and particularly to a 5I
The present invention relates to a nonlinear conduction quantum device having an S (semiconductor-insulator-semiconductor) structure and a method for manufacturing the same.

[Prior Art] Quantum devices that utilize the wave nature of electrons are gaining importance as next-generation new functional devices. In order to realize the wave nature of electrons in quantum devices, conventionally, MB
A common method was to use E (molecular beam epitaxial method) or MOCVD (metal-organic vapor phase epitaxy) to deposit thin film crystals with different constituent atoms and band gaps to form electron quantum levels.

[Problems to be Solved by the Invention] However, the techniques such as MBE'PMOCVD used to form the conventional quantum device described above, for example,
This method has problems such as requiring an ultra-high vacuum of about 1000 m or more, slow crystal growth resulting in poor efficiency, and requiring toxic gas.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor device with nonlinear conduction characteristics that can be easily manufactured when a carrier quantum level is formed with an extremely simple structure.

[Means for solving the problem] The above problem includes two semiconductor substrates and a thin film insulating layer sandwiched between the two semiconductor substrates, and an interface between the two semiconductor substrates and the thin film insulating layer. This is achieved by a semiconductor device characterized by having nonlinear conduction characteristics due to the resonant tunneling effect of quantized two-dimensional carriers formed in the semiconductor device.

The above problem also includes a step of forming thin film insulating layers on two semiconductor substrates, and a step of bonding the thin film insulating layers on the two semiconductor substrates to each other to form a semiconductor-insulator-semiconductor structure. This is achieved by a method of manufacturing a semiconductor device characterized by having the following characteristics.

[Function]) That is, in the present invention, a triangular potential well is formed at the interface between the semiconductor substrate and the thin film insulating layer by an SIS structure in which a thin film insulating layer is sandwiched between two semiconductor substrates, and a triangular potential well is further formed in this triangular potential well. Utilizing the fact that the accumulated two-dimensional carriers are quantized, the quantum levels of the two-dimensional carriers formed in the triangular potential wells on both sides of the thin film insulating layer are relatively changed, and the quantum levels on both sides are changed. A large resonant tunneling current flows only when either of them matches, thereby realizing nonlinear current-voltage characteristics.

[Solid line example] Hereinafter, the present invention will be specifically described based on a solid line example.

FIG. 1 is a cross-sectional view showing a nonlinear conduction quantum device according to an embodiment of the present invention.

An InAs oxide film 6 with a thickness of 100 to 200 mm is sandwiched between two semiconductor substrates, for example (11A S substrates 2 and 4), forming a SISwJ structure. On top, for example, Pb (lead)
An ohmic electrode 8°10 consisting of the following is provided.

Next, FIG. 2 shows the energy band of such a 5ISI nonlinear conduction quantum device.

At the interface between the InAs substrates 2 and 4 and the InAs oxidized WA 6, carrier density decreases, resulting in band gap bending. Two-dimensional electrons are accumulated in this part.

When the InAs substrate 2.4 and the InAs1l film 6 are in contact, the bandgap curve is steep, so a triangular potential well 12.1 is formed in the conduction band at the interface.
4 is formed. As shown in the band diagram of the degenerate electron system in Figure 2, this triangular potential well 12.1
The two-dimensional electrons accumulated in the electron beam 4 are subjected to a quantum one, and quantum levels El, E2, . . . are formed, respectively.

Next, the operation will be explained using FIG.

InAs substrate 2111! A positive voltage is applied to the ohmic electrode 8 of l, and the ohmic voltage vf! of the TnAs substrate 4 side is applied. When a negative voltage is applied to each of 10 and 10, as shown in FIG. ．． ... are shifted from each other, and none of the quantum levels El, E2 . ...will no longer be possible. Therefore I
Between the nAs substrates 2 and 4 is a sufficiently thin InAs substrate.
Only a tunnel current that passes through the oxide film 6 due to the l-channel effect flows, and the current value is small.

Next, as the voltage applied to the ohmic voltages [8 and 10 on the top and bottom surfaces of the InAs substrates 2 and 4 is increased, as shown in FIG. 3(b), the triangles on the InAs substrate 2 side are The quantum level E2 formed in the potential well 12 coincides with the quantum level E1 formed in the triangular potential well 14 of the InAs substrate. Therefore, since a resonant tunnel effect occurs between both levels,
A large resonant channel current passes through the InAs oxide film 6 and flows between the InAs substrates 2 and 4.

The measurement results of the current-voltage characteristics obtained in this manner are shown in FIG.

Corresponding to FIG. 3(a), two-dimensional electron quantum levels El, E2, . ... do not match, the current is decreasing as shown at point A. On the other hand, corresponding to FIG. 3(b),
Quantum levels El, B2. formed in the triangular potential well 12°14. If any of them match, the current is increasing as shown at point B. In this way, the current flowing between the InAs substrates 2 and 4 is not linear with respect to the applied voltage, but has a wavy shape. That is, it exhibits nonlinear characteristics. The graph in FIG. 4 was measured at a temperature of 4.degree. 2K.

As described above, according to this embodiment, the InAs substrate 2.4 and the InAs oxide film 6 having a thickness of 100 to 200 layers are sandwiched between the InAs substrates 2.4 and 2.4 by the 5ISvJ structure.
A triangular potential well 12.14 is formed in the conduction band at the interface of the AsAs oxide film 6, and the two-dimensional electrons accumulated in this triangular potential well 12.14 are quantized,
Quantum level E1. E2. ... is formed.

By applying a predetermined voltage between the InAs substrates 2 and 4, the two-dimensional electron quantum level E1. E2. . . , the quantum levels El, E2 . ... do not match, a small tunnel current flows and the quantum level E1. E2.
. . . if any of them match, there is a large co-I'! +
', l, it is possible to realize a nonlinear current-voltage characteristic where the channel current flows.

Next, a method for manufacturing the nonlinear conduction quantum device shown in FIG. 1 will be explained using FIG. 5.

Two wafer-shaped InAs substrates 2 and 4 are heat-treated in an oxidizing atmosphere to form InAsnAs oxide films 6a each having a thickness of 50 to 100 layers on both sides of the InAs substrates 2 and 11 (see FIG. 5). a)).

Next, the InAS oxide film 6a on the InAs substrates 2 and 4,
6b is bonded and heat treated to form InAs substrates 2 and 4.
Paste together. At this time, the IIIAS oxide film 6a is sandwiched between the InAs substrates 2 and 4.

6b is an InAs oxide film 6 having a thickness of 100 to 200 μm. In this way, the SIS structure is formed (see FIG. 5(b)).

Next, the InAsnAs oxide film 6 is bonded to the
The InAs oxide films 6a and 6b on both sides of the As substrate 2.4 are removed. After evaporating PB on the exposed top and bottom surfaces of the InAs substrates 2 and 4, heat treatment is performed to form an alloy to form ohmic conductors 8 and 10 (see FIG. 5(c)).

In this way, a nonlinear conduction quantum device having nonlinear current-voltage characteristics is fabricated.

As described above, according to the manufacturing method of this embodiment, MBE'? A nonlinear conduction quantum device can be manufactured extremely easily using a so-called wafer bonding technique without using a technique such as MOCVD.

0 In the above embodiment, the ohmic electrode i8.0 formed on the InAs substrate 24. Although Pb is used as io, Nb (niobium) may be used instead.

Further, in the above embodiment, InA is used as the semiconductor substrate.
By using an s-substrate, quantized two-dimensional electrons are formed at the interface with the InAs oxide film, and the resonant tunneling effect of these two-dimensional electrons is used to achieve nonlinear conduction characteristics. By changing to another semiconductor material, it is also possible to realize nonlinear conduction characteristics using the two-dimensional hole resonance tunneling effect.

[Effects of the Invention] As described above, according to the present invention, by using the SIS structure in which a thin film insulating layer is sandwiched between two semiconductor substrates, a triangular bodential is formed at the interface between the two semiconductor substrates and the thin film insulating layer. Nonlinear current-voltage characteristics can be realized by utilizing the resonant one-channel effect of quantized two-dimensional carriers accumulated in the well.

Further, according to the present invention, a semiconductor device having such nonlinear conduction characteristics can be manufactured extremely easily by a technique of bonding two semiconductor substrates on which thin film insulating layers are formed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a nonlinear conduction quantum device according to an embodiment of the present invention, FIG. 2 is an energy band diagram of the nonlinear conduction quantum device of FIG. 1, and FIG. 3 is a cross-sectional view of the nonlinear conduction quantum device of FIG. FIG. 4 is an energy band diagram for explaining the operation, FIG. 4 is a graph showing the characteristics of the nonlinear conduction quantum device shown in FIG. 1, and FIG. 5 is a process chart showing a method for manufacturing the nonlinear conduction quantum device shown in FIG. 1. In the figure, 2.4...InAs substrate, 6.6a, 6b---...-1n, As oxide film, 8.1
0...Ohmic electrode, 12.14...
・Triangular potential well.

Claims (1)

[Claims] 1. Comprising two semiconductor substrates and a thin film insulating layer sandwiched between the two semiconductor substrates, quantization formed at an interface between the two semiconductor substrates and the thin film insulating layer. A semiconductor device characterized by having nonlinear conduction characteristics due to the resonance tunneling effect of two-dimensional carriers. 2. Forming a thin film insulating layer on each of the two semiconductor substrates; and bonding the thin film insulating layers on the two semiconductor substrates to each other to form a semiconductor-insulator-semiconductor structure. A method for manufacturing a featured semiconductor device.