Electronic and vibrational Raman studies of the superconducting proximity effect in Nb:InAs heterojunctions

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:466571

Dorsten, J F; Abeyta, A; Roshchin, I; Greene, L H ^[1]

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1. Univ. of Illinois, Urbana, IL (United States)

Electronic Raman scattering from coupled phonon-plasmon model and vibrational scattering from LO phonon modes confined to that near-surface region of InAs have been used to probe the change electron density, n, associated with transition through T. of a thin Nb film electrode. In contrast to the vast majority of other III-V surfaces, InAs displays an electron charge accumulation region (CAR). At the doping densities used in these experiments the width of the CAR is of the order 50A. Confining electrons to such a small region of space gives rise to quantum size effects, and the result in the Raman spectrum is large-q contributions to the scattering mechanism for LO phonons. Because the LO phonon is effectively screened in the bulk of the InAs the relative magnitudes of the phonon and coupled phonon-plasmon bands can be used to monitor relative changes in the n in the near-surface region. Experiments with Nb:InAs heterojunctions make use of direct excitation through the Nb overlayer and demonstrate that cooling the superconductor through its transition temperature, can have a dramatic effect on n near the interface.

• OSTI ID: 466571
• Report Number(s): CONF-951017--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
CORRELATIONS
ELECTRON DENSITY
EXCITATION
HETEROJUNCTIONS
INDIUM ARSENIDES
PHONONS
PROXIMITY EFFECT
SUPERCONDUCTIVITY
TRANSITION TEMPERATURE