Field Effect and Strongly Localized Carriers in the Metal-Insulator Transition Material VO2

Abstract

The intrinsic field effect, the change in surface conductance with an applied transverse electric field, of prototypal strongly correlated VO2 has remained elusive. Here we report its measurement enabled by epitaxial VO2 and atomic layer deposited high-κ dielectrics. Oxygen migration, joule heating, and the linked field-induced phase transition are precluded. The field effect can be understood in terms of field-induced carriers with densities up to ∼5×1013 cm-2 which are strongly localized, as shown by their low, thermally activated mobility (∼1×10-3 cm2/V s at 300 K). These carriers show behavior consistent with that of Holstein polarons and strongly impact the (opto)electronics of VO2.