Photoelectron spectroscopic and surface resistance measurements of TiO2 and V2O5 after rare‐gas sputtering

Abstract

AbstractInsulating to semiconducting transformation was observed for surface layers of the transition metal oxides exposed to 1.5–15 keV He+, Ar+ and Xe+ ions. The surface electrical conductivity increased with the fluence of the ion beams and reached ∼10Ω−1 cm−1 at a fluence of 1 × 1017 Ar+ cm−2. Core‐line splittings in the metal 2p region and preferential losses of the surface oxygen observed in the x‐ray photoelectron spectra give evidence of the formation of the reduced chemical species Ti(II), Ti(III) and V(III). The ion bombardment also brought about the appearance of a new peak near the Fermi level in the UV photoelectron spectra. These observations suggest that electrons in the O 2p orbital are transferred to the 3d‐derived non‐bonding level by the losses of atomic oxygen and thus behave as charge carriers, which causes an increase in electrical conductivity.