STM studies of Au nano-clusters on TiO2(110)

The TiO2(1 1 0) surface, carefully characterized by STM, was used as a supp ort for Au nano-clusters grown by thermal evaporation. The atomic bright ro ws imaged on the clean 1 x 1 TiO2(1 1 0) surface at the negative sample bia s voltage are interpreted as bridging oxygen atoms. Gold was deposited at r oom temperature in doses corresponding to 0.013, 0.08 and 0.2 of the nomina l Au(1 1 1) monolayer. Preferential Au nucleation along the substrate step edges was observed. The nucleation process determines the initial depositio n for the coverage below 0.1 Au monolayer. In this growth regime, the distr ibution of the apparent cluster height measured at + 1.7V sample bias is pe aked around values spaced by about 0.2 nm, corresponding roughly to the Au( 1 1 1)interlayer spacing. The lowest clusters have a monoatomic height. For the higher Au coverage 3D-growth is observed. The apparent cluster height depends strongly on the bias voltage. (C) 2001 Elsevier Science Ltd. All ri ghts reserved.