Magnetodielectric Coupling in Nonmagnetic Au/GaAs:Si Schottky Barriers

TL;DR

This paper discovers a giant negative magnetocapacitance effect in non-magnetic Au/GaAs:Si Schottky barriers, caused by magnetic field-induced changes in impurity ionization energies, revealing new magnetodielectric coupling mechanisms.

Contribution

It reports a novel magnetodielectric coupling in non-magnetic Schottky barriers due to impurity ionization energy shifts under magnetic fields.

Findings

Giant negative magnetocapacitance (>20%) observed.

Magnetic field increases impurity binding energy.

Shift in built-in potential not due to Schottky barrier height change.

Abstract

We report on a heretofore unnoted giant negative magnetocapacitance (>20%) in non-magnetic Au/GaAs:Si Schottky barriers that we attribute to a magnetic field in-duced 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/Cdep^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.