Electric field-induced carrier accumulation at the vanadium dioxide-dielectric interface*

Classical rigid band semiconductors respond to an electric field at a dielectric interface by accumulating or depleting carriers at the interface. We investigate electrostatic field-effects in thin film devices formed from the prototypical, strongly-correlated insulator, vanadium dioxide VO$_{2}$. This material exhibits a temperature driven insulator to metal transition near room temperature. Therefore, non-trivial electric field driven electronic effects can be anticipated. We find that excess carriers can be introduced in our devices with concentrations of up to $\sim$ 5x10$^{13}$cm$^{-2}$: these field induced carriers exhibit an activated low mobility at low temperatures that is characteristic of electron localization. Field-effect conductance modulation and depletion are highly inhibited with excess carriers confined near the interface. Signatures of defect-dominated scenarios are absent. The field-effect behavior that is exhibited by our VO$_{2}$ based devices is fundamentally different from that of a classical semiconductor.