Differential Conductance in Semiconductor-Superconductor Hybrid Structures

ORAL

Abstract

We construct a theory for calculating the differential conductance in semiconductor-superconductor hybrid structures that accounts for both the current carried by quasiparticles in the bulk superconductor and the contributions due to proximity effects induced in the semiconductor. Starting with a Blonder-Tinkham-Klapwijk (BTK) type approach, we show that the superconductor degrees of freedom can be conveniently integrated out and replaced by an interface `Green function' determined by the properties of the superconductor and the original outgoing-wave boundary conditions corresponding to quasiparticle propagation. We find that the features present in the differential conductance are associated with both semiconductor and bulk superconductor spectral features, with a relative strength that depends on the parameters of the structure. We systematically investigate the dependence of the differential conductance on the parameters of the system, including coupling strength, semiconductor band occupancy, and barrier transparency, and correlate our findings with recent experimental measurements on proximity-coupled semiconductor wires.

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Authors

  • John Stenger

    West Virginia University

  • Scott Cushing

    National Radio Astronomy Observatory, Jodrell Bank Centre for Astrophysics, New York University Abu Dhabi, Naval Research Laboratory, CSIRO Astronomy and Space Sciences, George Mason University, ASTRON, NASA Goddard Space Flight Center, University of Wisconsin-Milwaukee,, Station de radioastronomie de Nancay, Columbia Astrophysics Laboratory, Max-Planck-Institut fur Physik, West Virginia Univ, West Virginia University, Lehigh University, Fraunhofer Institute for Physical Measurement Techniques, Department of Microsystems Engineering (IMTEK), Pennsylvania State University, Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA, Massachusetts Institute of Technology, University of Minnesota, Pennsylvania State Univ, University of Maryland, Towson University, Department of Physics, Villanova University, University of Virginia, Boston University, Univ of Maryland-College Park, Harvard University, The Pennsylvania State Unversity, University of Wisconsin-Madison, McMaster University, California State University - Long Beach, National Chiao Tung University, National Chiao Tung University, Taiwan, Ohio University, University of Rennes, UMR CNRS 6251, Rennes, France, University of Bordeaux, UMR 5804, Floirac, France, University of Bordeaux, UMR 5255, Talence, France, Sandia National laboratories, Livermore, CA, Department of Chemistry, West Virginia University, Morgantwon, WV, The Pennsylvania State University, University of Toronto, Departamento de F\'isica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile, Cinvestav-Unidad Queretaro, Queretaro-76230, Mexico, Department of Physics and Astronomy, West Virginia University, Morgantown, WV-26505-6315, USA, The University of Arizona, TU Dortmund, Dortmund, Naval Air Warfare Center - Aircraft Division