Nature of donor states in V-doped SnO2

Abstract

The influence of vanadium doping on the electronic structure of SnO₂ has been studied by a range of techniques including X-ray and ultraviolet photoemission spectroscopy, as well as IR reflectance and magnetic susceptibility measurements. In contrast to Sb, V does not act as a shallow n-type dopant in SnO₂ and V substitution appears to be largely compensated by cation vacancies or oxygen interstitials. However, a state is apparent in ultraviolet photoemission toward the bottom of the bulk bandgap of SnO₂. This corresponds to electrons trapped on V^IV ions close to the surface of the doped material. The binding energy of the V^IV state in doped SnO₂ is compared with that in V-doped TiO₂ and the differences between the two materials are shown to be consistent with a simple dielectric model.