STOCHASTIC-MODEL FOR SURFACE EROSION VIA ION SPUTTERING - DYNAMICAL EVOLUTION FROM RIPPLE MORPHOLOGY TO ROUGH MORPHOLOGY

Surfaces eroded by ion sputtering are sometimes observed to develop mo rphologies which are either ripple (periodic) or rough (nonperiodic). We introduce a discrete stochastic model that allows us to interpret t hese experimental observations within a unified framework. We find tha t a periodic ripple morphology characterizes the initial stages of the evolution, whereas the surface displays self-affine scaling in the la ter time regime. Further, we argue that the stochastic continuum equat ion describing the surface height is a noisy version of the Kuramoto-S ivashinsky equation.