Energies and Atomic Structures of Grain Boundaries in Silicon: Comparison Between Tilt and Twist Boundaries

Abstract

ABSTRACTThe energies and atomic structures of tilt and twist boundaries in Si have been examined by using the tight-binding electronic theory, and the reason why twist boundaries are seldom found in polycrystalline Si has been investigated. About the frequently observed {122} Σ=9 and {255} Σ=27 tilt boundaries, the configurations without any coordination defects consistent with the electron microscopy observations have relatively small interfacial energies with small bond distortions. About the <111> Σ=7, <011> Σ=3 and <001> Σ = 5 twist boundaries, the configurations contain larger bond distortions or more coordination defects, and much larger interfacial energies than those of the tilt boundaries. The <001> twist boundaries have very complex structures as compared with the other twist boundaries, which can be explained by the morphology of the ideal surfaces. The stability of the tilt boundaries in Si can be explained by the viewpoint of the stable structural units consisting of atomic rings.