ABSTRACTPit nucleation has been observed in a variety of semiconductor thin films. We present a model in which pit nucleation is considered to arise from a near-equilibrium nucleation process in which the adatom concentration plays an important role. Although pits relieve elastic energy more efficiently than islands, pit nucleation is prevented if the adatom concentration is too high. Inhomogeneities in the adatom density on the surface due to three-dimensional islands enhance pit nucleation. Thermodynamic considerations predict several different growth regimes in which pits may nucleate at different stages of growth depending on the materials system and growth conditions. However kinetics must be taken into account to make direct comparisons to experimental observations. These comparisons show good agreement given the uncertainties in quantifying experimental parameters such as the surface energy.
Mechanisms for Surface Segregation in Compound Semiconductor Thin Films