Morphology of multilayer Ag/Ag(100) films versus deposition temperature: STM analysis and atomistic lattice-gas modeling - art. no. 085401

Scanning tunneling microscopy is used to analyze the nanoscale morphology o f 25 ML films of Ag deposited on Ag(100) at temperatures (T) between 55 and 300 K. A transition from self-affine growth to "mound formation" occurs as T increases above: about 140 K. The roughness decreases with increasing T up until 140 K in the self-affine growth regime, and then increases until a bout 210 K before decreasing again in the mounding regime. We analyze mound ing behavior via a lattice-gas model incorporating: downward funneling of d epositing atoms from step edges to lower fourfold hollow adsorption sites; terrace diffusion of adatoms with a barrier of 0.40 eV leading to irreversi ble island formation in each layer; efficient transport of adatoms along is land edges to kink sites, and downward thermal transport of adatoms inhibit ed by a step-edge barrier of 0.06-0.07 eV along close-packed step edges (bu t with no barrier along kinked or open steps). This model reasonably recove rs the T-dependence of not just the roughness, but also of the mound slopes and lateral dimensions above 190 K. To accurately describe lateral dimensi ons, an appropriate treatment of the intralayer merging of growing islands is shown to be critical. To describe behavior below 190 K, one must account for inhibited rounding of kinks by adatoms at island edges, as this contro ls island shapes, and thus the extent of open steps and of easy downward tr ansport. Elsewhere. we describe the low-T regime of self-affine growth (wit h no terrace diffusion) accounting for a breakdown of the simple downward f unneling picture.