Observation of the superconducting proximity effect in Nb/InAs and NbNx/InAs by Raman scattering

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Observation of the superconducting proximity effect in Nb/InAs and NbNx/InAs by Raman scattering

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Title: Observation of the superconducting proximity effect in Nb/InAs and NbNx/InAs by Raman scattering
Author: Roshchin, I. V.; Abeyta, A. C.; Greene, L. H.; Tanzer, T. A.; Dorsten, J. F.; Bohn, P. W.; Han, Sang-Wook, 1964-; Miceli, Paul F.; Klem, J. F.
Keywords: tunneling phenomena
point contacts
weak links
Josephson effects
electron states at surfaces and interfaces
Date: 2002-10-31
Publisher: American Physical Society
Citation: Phys. Rev. B 66, 134530 (2002)
Abstract: High-quality thin Nb and NbN films (60-100 Å) are grown on (100) n+-InAs (n=1019cm-3) substrates by dc-magnetron sputter deposition. Studies of the electronic properties of interfaces between the superconductor and the semiconductor are done by Raman scattering measurements. The superconducting proximity effect at superconductor-semiconductor interfaces is observed through its impact on inelastic light scattering intensities originating from the near-interface region of InAs. The InAs longitudinal optical phonon LO mode (237cm-1) and the plasmon-phonon coupled modes L- (221cm-1) and L+ (1100 to 1350cm-1), for n+=1×1019-2×1019cm-3 are measured. The intensity ratio of the LO mode (associated with the near-surface charge accumulation region, in InAs) to that of the L- mode (associated with bulk InAs), is observed to increase by up to 40% below the superconducting transition temperature. This temperature-dependent change in light scattering properties is only observed with high quality superconducting films and when the superconductor and the semiconductor are in good electrical contact. A few possible mechanisms of the observed effect are proposed.
URI: http://hdl.handle.net/10355/7461
ISSN: 1098-0121

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