First-principles determination of theΣ=13{510} symmetric tilt boundary structure in silicon and germanium

Abstract

We have examined a variety of structures for the {510} symmetric tilt boundary in Si and Ge, using tight-binding and first-principles calculations. These calculations show that the observed structure in Si is the lowest-energy structure, despite the fact that it is more complicated than what is necessary to preserve fourfold coordination. Contrary to calculations using a Tersoff potential, first-principles calculations show that the energy depends strongly upon the structure. A recently developed tight-binding model for Si produces results in very good agreement with the first-principles calculations. Electronic density of states calculations based upon this model show no evidence of midgap states and little evidence of electronic states localized to the grain boundary.