Scanning tunneling microscopy studies of submonolayer and multilayer Ag films deposited on Ag(100)
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Abstract
A comprehensive analysis of submonolayer and multilayer Ag films deposited on Ag(100) is performed. Extensive ultra-high vacuum Scanning Tunneling Microscopy (STM) experiments are presented revealing exotic equilibration pathways in the Ag adlayer, as well as novel growth modes in multilayer Ag films;Real-time STM imaging of adlayer dynamics at 295 K allows for the elucidation and quantification of various kinetic processes controlling the coarsening of two-dimensional (2D) submonolayer island distributions. Coarsening kinetics are analyzed using a mean-field Smoluchowski rate equation, which gives both a strongly size dependent island diffusion coefficient and an estimate of the size scaling exponent. Details of the coalescence process are also recorded with the STM. Island-island and island-step edge collision and coalescence forms exotic, 2D nanostructures on the surface, whose subsequent relaxation rates are quantified and analyzed with lattice-gas model simulations in order to elucidate the underlying atomistic mass transport processes;The temperature dependent surface morphology of multilayer Ag films on Ag(l00) is investigated using variable-temperature STM. Novel doubly non-monotonic behavior in roughness with temperature is observed for 25 monolayer (ML) films deposited between 54 and 300 K. Well-correlated mound structures are observed above 190 K, while self-affine films are shown to grow below 135 K. Additionally, the roughness exponent, beta, is estimated at 230 K, where 25 ML Ag films exhibit the largest interface width.