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

I. V. Roshchin, A. C. Abeyta, Laura Greene, T. A. Tanzer, J. F. Dorsten, P. W. Bohn, S. W. Han, P. F. Miceli, J. F. Klem

Research output: Contribution to journalArticlepeer-review


High-quality thin Nb and NbN films (60-100 Å) are grown on (100) n+-InAs (n= 1019 cm-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 (237 cm-1) and the plasmon-phonon coupled modes L- (221 cm-1) and L+ (1100 to 1350 cm-1), for n+ = 1 × 1019 - 2 × 1019 cm-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.

Original languageEnglish (US)
Article number134530
Pages (from-to)1345301-13453010
Number of pages12107710
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number13
StatePublished - Oct 1 2002

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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