Transport across meso-junctions of highly doped Si with different superconductors

TL;DR

This study investigates the transport properties of highly doped silicon meso-junctions with various superconductors using point contact Andreev reflection spectroscopy, revealing effects of interface barriers and proximity-induced superconductivity.

Contribution

It provides new insights into how interface transparency affects superconducting gap features in doped silicon-superconductor junctions.

Findings

Enhanced superconducting gap in low transparency Si-In contacts due to Schottky barrier.

No gap enhancement in high transparency Si-Nb and Si-Pb contacts, but presence of sub-gap features.

Proximity-induced interface superconductivity observed in high transparency junctions.

Abstract

We studied the transport properties of meso-junctions of semiconducting (Sm) highly doped Si with different superconductors (Sc) through point contact Andreev reflection (PCAR) spectroscopy. Spectra of low transparency point contacts between Si and In showed an enhancement in the superconducting energy gap of In. This was due to the effect of an additional gap arising from the Schottky barrier at the Sm-Sc interface. For higher transparency Si-Nb and Si-Pb point contacts, no gap enhancement was observed though there were weak sub gap features. These were due to proximity induced interface superconductivity known to occur for Sm-Sc junctions of high transparency.