We investigated the surface potential of TiO 2 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 (ΔV 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 TiO 2. These results will give us insights into ambient-dependent physical phenomena in oxide thin film nanostructures.
Bibliographical noteFunding Information:
H.K. and D.-W.K. were supported by the Quantum Metamaterials Research Center (2009-0063324) and the Basic Research Program (2010-0009344) through the National Research Foundation of Korea Grant funded by the Korean Ministry of Education, Science, and Technology. The SPM experiments and data analysis (H.K. and S.H.) were conducted at the Materials Science Division of Argonne National Laboratory, a U.S. DOE Office of Science Laboratory, operated under Contract No. DE-AC02-06CH11357.