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Large electric field effects of ultrathin films of BI/a Ge grown on a single crystal SrTiO3 substrates

Gloria Martinez-Arizala
University of Minnesota

a photo of Ms. Martinez-Arizala and her experimental apparatus

A large electric field effect was observed in ultrathin films of Bi/a Ge, quench condensed at liquid helium temperatures into single crystal SrTiO3 substrates. A Pt gate electrode was pre-evaporated on the back of the substrate. Insulating films exhibited a symmetric response to the gate voltage, with a maximum increase in conductivity of about 50% for the most insulating film. The symmetric effect disappeared as the superconductor insulator (SI) transition was approached. In the superconducting (metallic) state, the response was small and antisymmetric in the gate voltage. The variation of this effect with temperature, film thickness, and its relationship to the SI transition will be reported. The possible origins of this phenomena, including electron hole symmetry and electrostriction in SrTiO3, will be discussed.


Last Modified: 2007-09-21 at 12:09:05 -- this is in International Standard Date and Time Notation