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

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

Kjaergaard, M. (University of Copenhagen)
Suominen, H. J. (University of Copenhagen)
Nowak, M.P. (TU Delft QRD/Kouwenhoven Lab; TU Delft QuTech Advanced Research Centre; AHG University of Science and Technology; Kavli institute of nanoscience Delft)
Akhmerov, A.R. (TU Delft QN/Akhmerov Group; Kavli institute of nanoscience Delft)
Shabani, J. (University of California)
Palmstrøm, C. J. (University of California)
Nichele, F. (University of Copenhagen)
Marcus, C.M. (University of Copenhagen)

2017

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.

http://resolver.tudelft.nl/uuid:4e318e82-79e0-4228-b99a-3fd4c266944f

https://doi.org/10.1103/PhysRevApplied.7.034029

2331-7019

Physical Review Applied, 7 (3)

Institutional Repository

journal article

© 2017 M. Kjaergaard, H. J. Suominen, M.P. Nowak, A.R. Akhmerov, J. Shabani, C. J. Palmstrøm, F. Nichele, C.M. Marcus