Importance of the additional step-edge barrier in determining film morphology during epitaxial growth

A model of epitaxial growth based on steady-state assumptions is derived and shows that the decisive quantity determining the film morphology is the additional energy barrier at the step edges, i.e., the barrier to descend the step minus the surface-diffusion barrier. The model allows this barrier to be directly determined from experimentally observed film morphologies. It is applied to homoepitaxy on Ag(111) and Pt(111) where the additional barriers amount to ~150 and ~165 meV, respectively. In addition, this model provides new understanding of more complex processes, such as the surfactant effect of Sb on Ag(111) and reentrant growth on Pt(111).