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Optimized Structure for Superconducting Field Effect Transistors

IP.com Disclosure Number: IPCOM000036935D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 18K

Publishing Venue

IBM

Related People

Chi, CC: AUTHOR [+2]

Abstract

A technique is described whereby the proximity effect between superconductor and semiconductor materials, which make up the structure of superconducting field-effect transistors (FETs), is optimized so as to reduce coupling problems, which can occur when there is a mismatch in Fermi velocity between the materials.

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Optimized Structure for Superconducting Field Effect Transistors

A technique is described whereby the proximity effect between superconductor and semiconductor materials, which make up the structure of superconducting field-effect transistors (FETs), is optimized so as to reduce coupling problems, which can occur when there is a mismatch in Fermi velocity between the materials.

Typically, superconducting FET devices have a semiconducting channel which is structured so that the superconducting properties of source and drain can overlap. This requires a strong proximity effect between the superconductor and the semiconductor. However, it has been shown that this effect is sensitive to the boundary conditions at the superconductor/semiconductor interface [*]. In particular, the coupling between the materials is drastically reduced when there is a significant mismatch in Fermi velocity between the materials. The concept described herein provides a structure whereby the FET low carrier density superconductors are coupled with semiconductors in order to maximize the proximity effect.

Proximity effect structures in which the material match is optimized, in terms of Fermi velocity, can be obtained using the following equation:

(Image Omitted)

As a result, it is necessary to choose a superconductor that has an electron density of

For FET devices, it is necessary to have a small nSC so as to obtain a large gate response. For example, with 1017cm-3 InAs, where m* = 0.023, s...