Novel vertical silicon-membrane structure and its application to Josephson devices

Abstract

The authors present novel techniques for fabricating vertical silicon membranes having thicknesses below 100 nm and, in some cases, ∼40 nm. The combination of extreme membrane facet smoothness, near perfect parallelism, compatibility with epitaxial doped layers, and ability to be fabricated in either single structures or in dense arrays present unusual properties for application. As one specific application of this structure, the authors have fabricated a hybrid superconductor/semiconductor short-channel Josephson device. Since these vertical membrane structures are also compatible with high-mobility Si/Ge channel layers, the authors are currently extending this work to study the ballistic transport of Cooper pairs through discrete energy eigenstates formed by the quantum confinement within the thin semiconductor membrane.