Molecular-dynamics study on atomistic structures of amorphous silicon

Abstract

Structural characteristics of amorphous silicon (a-Si) have been examined by molecular-dynamics calculations using the Tersoff interatomic potential. It was confirmed that the computer-generated atomic configurations reproduce well the structural and dynamical properties of a-Si obtained experimentally. The a-Si networks contained two types of structural defect: threefold coordinated Si atoms (dangling bonds) and fivefold coordinated ones (floating bonds). The average bond length increased with the coordination number. Bond angles were distributed around 120° for the threefold coordinations, suggesting the existence of the atomic clusters constructed by sp2 bonding. On the other hand, they had peaks at ~60° and 90° for the fivefold coordinated atoms. Partial radial distribution functions revealed that the floating bonds have a tendency to cluster in the a-Si network.