AFM study on microstructures of metal films deposited on liquid substrates

We study the formation mechanism and microstructures of silver and gold thin films deposited on silicone oil surfaces by atomic force microscopy (AFM). The growth mechanism of the metallic films obeys the two-stage growth model. We find that the atomic compact clusters and ramified aggregates formed on the oil surfaces are composed of crystal grains with the size of the order of 101 nm. The most interesting phenomenon is that, as the nominal film thickness increases, the mean size of the grains in the ramified aggregates does not change obviously. The characteristic difference of the microstructures between the down and up surfaces of the continuous films is measured. The physical interpretation of the results is also presented