Dielectric Properties of SrTiO3 Epitaxial Film and Their Application to Measurement of Work Function of YBa2Cu3Oy Epitaxial Film

Abstract

The dielectric properties of SrTiO₃ epitaxial film were studied using film grown on oxide superconductor YBa₂Cu₃O _y . They were, to a certain extent, similar to those of the single-crystal bulk in terms of both temperature and electric field dependence, though the value of the dielectric constant was low, particularly at cryogenic temperatures. The observed dielectric properties were analytically expressed. Using the dramatic field dependence of the dielectric constant of the SrTiO₃ film in the Au-SrTiO₃-YBa₂Cu₃O _y metal-insulator-superconductor (MIS) structure, we determined the work function of (001)YBa₂Cu₃O _y epitaxial film to be ∼6.1 eV.