Magnetodielectric coupling in nonmagnetic Au/GaAs:Si Schottky barriers

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