Theoretical Analysis of Step Bunching Instability in presence of Misfit Strain and Ehrlich-Schwoebel Barrier

We develop a generic theoretical model to analyze step-flow of strained films, taking into account effects of both strain-induced step-step interaction and Ehrlich-Schwoebel (ES) step-edge barrier. In general, the strain induces a step bunching instability; a positive ES barrier (a barrier for an adatom to go downward over a step) stabilizes the step flow, while a negative ES barrier (a barrier for an adatom to go upward over a step) destabilizes the step flow. We will discuss the stability of step-flow growth in terms of relative strength of strain and ES barrier effects and compare with computer simulations.