Defects were introduced onto an atomically clean TiO2(110) surface in a controllable manner via bombardment by 0.5keV Ar+ ions, and the resultant material was probed with scanning tunnelling microscopy and x-ray photoelectron spectroscopy. It was shown that ion bombardment leads to a change of stoichiometry and the formation of vacancy clusters, while annealing after prolonged bombardment forms regular rectangular cavities with single-atomic-layer steps. It was concluded that curvature-dependent sputtering in combination with adatom and vacancy diffusion was responsible for the observed structures.

Sputtering-Induced Vacancy Cluster Formation on TiO2(110). Karmakar, P., Liu, G.F., Yarmoff, J.A.: Physical Review B, 2007, 76[19], 193410