JPH02114679A - Field effect josephson transistor - Google Patents

Abstract

PURPOSE:To obtain a field effect Josephson transistor adapted for mass production by a method wherein a substrate electrode is provided in series with a tunnel film provided to the side wall inside the gap between a source and a drain electrode, and a gate electrode which controls a tunnel current with an electric field is formed through the intermediary of a dielectric film. CONSTITUTION:A field effect Josephson transistor is composed of an SiO2 2 formed on the surface of an Si 1, a gate electrode 5 formed through the etching of the rear of the Si 1, a source electrode 3 and a drain electrode 4 provided separate from each other by a slightly wide gap onto the SiO2 2 on the gate electrode 5, a field insulating film 7 thickly provided on the surface of the source electrode 3 and the drain electrode 4, a tunnel film 6 formed on the side wall as thick as tens of Angstrom , and a substrate electrode 3 formed so as to fill the slightly wide gap. Therefore, two Josephson effect transistors are so constituted as to be connected with each other in series, and when a gate electrode is separately provided to each of the transistors, the transistors can function as a two gate field effect Josephson transistor, so that a field effect Josephson transistor structure adapted for the mass production can be offered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] The present invention relates to the structure of a field-effect Josephson transistor.

[Prior Art 1] Conventionally, there has been a field effect type Josephson transistor as shown in a cross-sectional view in FIG. That is,
5iOi12 is formed on a 5ill substrate, and the SiO+
Using 12 as a dielectric film, a gate electrode 15 is formed using Nb or the like in a hole made on the back surface of 5i11.
The source electrode 13 and the drain electrode [i14] are formed of Nb or the like so as to form a tunnel gap 16 of several tens of people above.

[Problem to be solved by the invention 1 However, according to the above-mentioned conventional technology, several tens of people
The problem is that it is extremely difficult to form the gap using photolithography and etching techniques.

It is an object of the present invention to solve the problems of the prior art and to provide a field-effect Joseph transistor structure that can be mass-produced.

[Means for Solving the Problems 1] In order to solve the above problems, the present invention relates to a field-effect Josephson transistor, in which a source electrode and a drain electrode are provided with a gap, and the source electrode and the drain electrode are separated from each other. A tunnel film is provided on the inner wall of the gap, a substrate electrode is provided in series with the tunnel film, and a gate electrode for controlling the electric field of the tunnel current flowing through the tunnel film is formed via a dielectric film.

[Example] Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 is a sectional view of a field effect type Josephson transistor showing one embodiment of the present invention. That is, 5iOz2 is formed on the surface of the Sil, the back surface of the Sil is etched to form the gate electrode 5, and the 5iOz2 on the gate electrode 5 is etched.
A source electrode 3 and a drain electrode 4 are provided on iO22 with a slightly wide gap, a field insulating film 7 is provided thickly on the surfaces of the source electrode 3 and drain electrode 4, and (
A tunnel film 6 with a thickness of several tens of layers is formed on the wall of the HI 3, and a substrate electrode 8 is formed so as to fill a slightly wide gap in the HI 3.

In addition, the material of the electrodes is Nb or Y+ BagCus.
There are superconductors such as O, and Nb as a tunnel film.
There are dielectric films such as O and SiO□.

Further, the substrate does not need to be made of Sil, but may be made of an insulator such as glass, and in this case, the gate electrode will be formed in layers on the glass substrate.

According to the present invention, exactly two Josephson effect elements are connected in series, and when the gate electrodes are attached independently, it also functions as a two-gate field effect Josephson transistor.

[Effects of the Invention] The present invention has the advantage of providing a field-effect Josephson transistor structure that can be mass-produced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a field effect type Josephson transistor showing one embodiment of the present invention. FIG. 2 is a cross-sectional view of a field effect Josephson transistor according to the prior art. 1. 2. 3. 4゜5. 6 ・ 7 ・ ・ ・ 8 ・ ・ ・ l 6 ・ ・ ・ Si S 10° Source electrode Drain electrode Gate electrode Tunnel film Field insulating film Substrate electrode Tunnel gap and above Applicant Seiko Epson Corporation

Claims (1)

[Claims] A source electrode and a drain electrode are provided with a gap, a tunnel film is provided on the inner wall of the gap between the source electrode and the drain electrode, a substrate electrode is provided in series with the tunnel film, and a substrate electrode is provided in series with the tunnel film. A field-effect Josephson transistor is characterized in that a gate electrode for electric field control of a tunnel current flowing through the transistor is formed through a dielectric film.