Tight-binding-molecular-dynamics investigation of the atomic and electronic structure properties of a-C, a-Si and a-SiC

摘要

Molecular dynamics simulations based on the sp{sup}3s{sup}* tight-binding force model is employed to calculate the atomic and electronic properties of amorphous tetrahedral silicon (a-Si), carbon (a-C), and silicon carbide (a-SiC). The two sets of the amorphous samples are generated from melts and dilute vapors. The vapor-based samples of 128 atoms are less topologically ordered than the 64-atom samples obtained from the melts. The procedure is used to investigate the electronic distribution in the band gap region. The changes in the density of states caused by a presence of coordination defects, strongly distorted tetrahedral species (and homo-polar bonds in the case of a-SiC) are examined. The computed characteristics were found to be in rather good agreement with the results from ab initio pseudo-potential calculations.