Transparent Semiconductor-Superconductor Interface and Induced Gap in an Epitaxial Heterostructure Josephson Junction

Journal article (2017)

Authors

M. Kjaergaard University of Copenhagen
Henri J. Suominen University of Copenhagen
M.P. Nowak QRD/Kouwenhoven Lab - QuTech Advanced Research Centre , Kavli institute of nanoscience Delft, QuTech Advanced Research Centre, AHG University of Science and Technology
A.R. Akhmerov Kavli institute of nanoscience Delft, QN/Akhmerov Group - AS
J. Shabani University of California
C. J. Palmstrøm University of California
Fabrizio Nichele University of Copenhagen
C.M. Marcus University of Copenhagen
Research Group
QN/Akhmerov Group (AS) (TU Delft)
Copyright: © 2017 M. Kjaergaard, H. J. Suominen, M.P. Nowak, A.R. Akhmerov, J. Shabani, C. J. Palmstrøm, F. Nichele, C.M. Marcus
DOI: https://doi.org/10.1103/PhysRevApplied.7.034029
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Published Date

2017

Language

English

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Faculty

Applied Sciences

Department

QN/Quantum Nanoscience

Research Group

QN/Akhmerov Group

Abstract

Measurement of multiple Andreev Reflection (MAR) in a Josephson junction made from an InAs quantum well heterostructure with epitaxial aluminum is used to quantify a highly transparent effective semiconductor-superconductor interface with near-unity transmission. The observed temperature dependence of MAR does not follow a conventional BCS form but instead agrees with a model in which the density of states in the quantum well acquires an effective induced gap, in our case, 180 μeV, close to that of the epitaxial superconductor, indicating an intimate contact between Al and the InAs heterostructure. The carrier density dependence of MAR is investigated using a depletion gate revealing the subband structure of the semiconductor quantum well, consistent with magnetotransport experiments of the bare InAs performed on the same wafer.