The impact of junction transparency in driving phase-coherent charge transfer across diffusive semiconductor-superconductor junctions is demonstrated. We present conductivity data for a set of Nb-InAs junctions differing only in interface transparency. Our experimental findings are analyzed within the quasiclassical Green’s-function approach and unambiguously show the physical processes giving rise to the observed excess zero-bias conductivity.

• Received 20 December 1999

DOI:https://doi.org/10.1103/PhysRevB.62.9831