Carrier transport in mesoscopic silicon-coupled superconducting junctions

Abstract

An overview is presented of experimental results on supercurrent flow and transport at finite voltages in a well-characterized, sandwich-type superconductor-semiconductor-superconductor junction. Carrier transport through the structure is found to be dominated by the interfaces. At low temperatures, inelastic scattering is negligible in the intermediate silicon layer and the system is mesoscopic. Application of a voltage results in a strongly nonthermal carrier distribution in the bulk of the semiconductor. The details of the distribution depend on elastic and Andreev scattering at the interfaces and are directly reflected by the measured current-voltage characteristics. The supercurrent is well described by a recent theory for the proximity effect that takes into account the reduction of the superconducting order parameter across the superconductor-semiconductor interface. Supercurrent measurements to identify a possible interplay between the superconductor phase and the single carrier phase in the semiconductor are discussed.