Switching of band bending at the nonreactiveCsOx/GaAs(110) interface

Abstract

The behavior of band bending in nonreactive interfaces between thin ${\mathrm{CsO}}_{\mathrm{x}}$ films and GaAs(110) is studied by photoemission. Successive cesium and oxygen exposures change the ${\mathrm{CsO}}_{\mathrm{x}}$ stoichiometry in a way that leads to a back-and-forth switching of overlayer metallicity and band bending. For both n- and p-GaAs(110), oxygen-rich nonmetallic overlayers create almost flat-band conditions, while cesium-rich metallic overlayers result in Fermi-level positions close to midgap. These observations demonstrate the dominant influence of metal-induced gap states in nonreactive metal-semiconductor interfaces.