a Study of SILVER/SILVER(100) Thin Film Growth with Scanning Tunneling Microscopy.

We used STM to study metal thin film growth processes. The following are main conclusions: (1) Large metal cluster diffuse on Ag(100) surface. The metal-metal system large adatom cluster diffusion is reported for the first time. The evaporation-condensation of adatoms dominating the vacancy cluster diffusion process is suggested. The diffusion coefficients is on the order of rm 10^ {-18} cm^2s^{-1}. (2) Metal film evolution behaviors at different coverage regime are examined. At low coverage, cluster diffusion dominates the coarsening process. At high submonolayer coverage, vacancy cluster repining dominates the process. At moderate coverage, edge-running dominates the process. (3) The vacancy cluster diffusion is also observed. The vacancy were formed by controlling the deposition flux and film coverage. The method is simple and offers similar advantages of the sputtering method. The diffusion coefficients is on the order of rm 10^{-18} cm^2s^{-1}, is smaller than that of adatom clusters, and has a scaling factor alpha roughly close to 0.5 in D ~ N^{-alpha }. The evaporation-condensation of vacancy monomers dominating the vacancy cluster diffusion process is suggested. (4) We have presented a number of observations of dynamical phenomena of Ag cluster on Ag (100) with UHV -STM. Ag cluster on Ag (100) at room temperature are mobile. The interaction between clusters and between clusters and surface steps are mediated via 2D dilute adatom gas on the terrace and different adatom concentrations around clusters and steps. Background gases and impurities on cluster edges can strongly affect film coarsening process. The former can enhance clusters dissolution, but the latter can stabilize the local structure and geometry of the Ag film.