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Shot-noise and conductance measurements of transparent superconductor / two-dimensional electron gas junctions

B. -R. Choi·A. E. Hansen·T. Kontos·C. Hoffmann·S. Oberholzer·W. Belzig·C. Schoenenberger·T. Akazaki·H. Takayanagi
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Abstract

We have measured the conductance and shot-noise of superconductor-normal metal (S-N) junctions between a Niobium (Nb) film and a 2-dimensional electron gas (2DEG), formed in an InAs-based semiconductor heterostructure. Adjacent to the junction, the 2DEG is shaped into a submicrometer beam-splitter. The current shot-noise measured through one arm of the beam-splitter is found to be enhanced due to Andreev reflection. Both noise and conductance measurements indicate that the Nb-2DEG interface is of high quality with a transparency approaching approx. 60-70 %. The present device can be seen as a quasi-ballistic S-N beam-splitter junction.

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B. -R. Choi, A. E. Hansen, T. Kontos, C. Hoffmann, S. Oberholzer, W. Belzig, C. Schoenenberger, T. Akazaki, H. Takayanagi. 2004-10-25. Shot-noise and conductance measurements of transparent superconductor / two-dimensional electron gas junctions. https://doi.org/10.1103/physrevb.72.024501

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