Unstable epitaxy and pattern formation on singular and vicinal surfaces

Theoretical results for unstable homoepitaxy due to additional barriers to hopping at step edges are reviewed. Using both kinetic Monte Carlo simulations and numerical integration of a continuum equation, it was demonstrated that, on a singular surface, pyramidal features (mounds) appear whose size and slope increases according to a power law. On a vicinal surface, ripples are created due to an instability of step edges. The ripples then undergo a secondary instability and break-up leading to a surface morphology indistinguishable from the one observed on the singular surface. In addition, deposition noise is shown to be an important factor in mound coarsening during unstable homoepitaxial growth. Computer simulations identify two regimes, high-temperature deterministic coarsening and a low-temperature noisy regime. (C) 1998 Elsevier Science Ltd. All rights reserved.