Magnetodielectric Coupling in Nonmagnetic Au/GaAs:Si Schottky Barriers

摘要

We report on a heretofore unnoted giant negative magnetocapacitance (>20%) innon-magnetic Au/GaAs:Si Schottky barriers that we attribute to a magnetic fieldin-duced increase in the binding energy of the shallow donor Si impurity atoms.Depletion capacitance (Cdep) dispersion identifies the impurity ionization andcapture processes that give rise to a magnetic field dependent density ofionized impurities. Internal photoemission experiments confirm that the largefield-induced shifts in the built-in potential, inferred from 1/Cdep^2 vsvoltage measurements, are not due to a field-dependent Schottky barrier height,thus requiring a modification of the abrupt junction approximation thataccounts for the observed magnetodielectric coupling.