Self-organization of oxide nanodots generated by low energy Ar+ bombardment on TiO2(110)-(1 x 2)

Defect sites generated by low energy Ar* bombardment (0.5-1.5 keV) at room temperature and the effect of subsequent annealing were studied on a TiO2 (1 1 0)-(1 x 2) surface by STM. It was found that, due to the effect of ion bombardment, the row structure of the reconstructed TiO2 (1 1 0)-(1 x 2) surface transforms into a granular structure where the OD nanodots exhibit a rather narrow size-distribution at about the diameter of 2 nm. The ordering of these dots can be induced by a slight thermal treatment at 500-700 K resulting in 1D strings along the crystallographic orientation of [0 0 1]. In this stage the surface terraces show (1 x 1) structure. Due to the effect of further annealing at 900 K the surface converts into a (1 x 2) reconstructed arrangement. The latter process is accompanied by the dissolution of the out-rising dots and strings formed in the previous treatments. It is assumed that the composition of the uniform nanodots is probably (Ti2O3)(n) where n varies between 4 and 6. (C) 2001 Elsevier Science Ltd. All rights reserved.