Nanoscale fabrication on a clean TiO2(110)1×2 surface by scanning tunnel microscopy

Abstract

The nanoscale restructuring process induced by the tunneling current was studied on a TiO2(110)1×2 reconstructed surface. The threshold parameters of 0.1 nA and +3.5 V were found. Below the critical voltage (even in the case of two orders of magnitude higher tunneling current), no change of the original surface structure appears. Above the threshold bias, the evolution of the process depends on the current: (i) for lower current (0.1–1 nA), only an outrising feature (average diameter of 3 nm, corrugation 1 nm) appears and the process saturates in the time scale of 10–20 s; (ii) for the higher currents 1–10 nA, the structural transformation begins with an increasing hump formation followed by a developing of a craterlike hollow structure (etching process). According to the results of the spectroscopic measurements, it is very likely that the created humps are composed of more reduced stoichiometric oxide phase. The facts that the presented process starts only above a threshold bias and the intensity of the tunneling current has great influence on the volume of the created structure strongly suggest a mechanism where a resonant electron excitation induced surface decomposition plays an important role.