Ambient effects on electric-field-induced local charge modification of TiO2

Abstract

We investigated the surface potential of TiO2 single crystals using scanning probe microscopy (SPM) under different gas environment. The SPM tip-induced electrical stress resulted in reversal in the surface potential, V-surf, polarity only in H-2/Ar (Delta V-surf = 0.30 eV) and not in Ar and O-2. Quantitative measurement of the influence of ambient gas on the surface potential led us to develop a model where the adsorbed oxygen molecules and oxygen vacancies interact to change their relative concentration leading to different surface potential in TiO2. These results will give us insights into ambient-dependent physical phenomena in oxide thin film nanostructures. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3675630]