Kinetic pathways leading to layer-by-layer growth from hyperthermal atoms:: A multibillion time step molecular dynamics study

We employ multibillion time step embedded-atom molecular dynamics simulations to investigate the homoepitaxial growth of Pt(111) from hyperthermal Pt atoms (E-Pt=0.2-50 eV) using deposition fluxes approaching experimental conditions. Calculated antiphase diffraction intensity oscillations, based on adatom coverages as a function of time, reveal a transition from a three-dimensional multilayer growth mode with E-Pt < 20 eV to a layer-by-layer growth with E-Pt >= 20 eV. We isolate the effects of irradiation-induced processes and thermally activated mass transport during deposition in order to identify the mechanisms responsible for promoting layer-by-layer growth. Direct evidence is provided to show that the observed transition in growth modes is primarily due to irradiation-induced processes which occur during the 10 ps following the arrival of each hyperthermal atom. The kinetic pathways leading to the transition involve both enhanced intralayer and interlayer adatom transport, direct incorporation of energetic atoms into clusters, and cluster disruption leading to increased terrace supersaturation.