Ag clusters on ultra-thin, ordered SiO₂ films

Scanning tunneling microscopy (STM) and low energy electron diffraction have been used to optimize the key synthetic parameters for the preparation of oriented, SiO₂ films on Mo(1 1 2). Extremely flat, ultra-thin, single-crystalline SiO₂ films have been prepared via deposition of silicon, its subsequent oxidation, followed by an anneal. Highly resolved STM images have been obtained for the first time on these films. At room temperature, Ag clusters grow two-dimensionally on these oriented films with a preferred orientation and sinter with a bimodal size distribution upon exposure to elevated pressures (160 mb and 60 min) of oxygen. Annealing the as-deposited Ag clusters at elevated temperatures (600 K) in ultra-high vacuum also leads to sintering.