Treatment of electrostatic interactions at the Si(100)-SiO2 interface

Silica in equilibrium with silicon is known to be partly crystalline. Because of crystallographic constraints, models proposed so far (cristobalite as well as tridymite) deal with polar surfaces of silica, which are expected to be highly unstable, In this paper, using both exact treatments of simplified models and Monte-Carlo simulations of the real system with effective potentials, we show how the system compromises to decrease the electrostatic energy. We also investigate the role of electrostatic interactions on the formation of oxygen vacancies at the Si-SiO2 interface. Using a tight binding approach, implications of these interactions on mid-gap surface states in silica are also discussed. Copyright (C) 1998 Elsevier Science B.V.