High-temperature annealing of amorphous silicon using tight-binding forces

Abstract

We present a simulation of high-temperature annealing of a model of amorphous silicon, computed using a molecular dynamics method with forces from a tight-binding total energy model, to approach a structure that is only dependent on tight-binding energetics. The annealing begins with a perfectly four-fold coordinated continuous random network structure. The annealing process is maintained for about 1 ns at 1300 K. We monitor the structure during the annealing, and confirm that it retains the coordination and radial distribution structure of the amorphous solid, rather than those of a liquid. We also monitor the change in network connectivity, to determine how much of the original bonding network remains. We find that most of the atoms have changed most of their neighbours, and nearly all of the rings in the original structure have been eliminated. The annealed structure is then cooled and relaxed to an energy minimum.

Acknowledgments

We acknowledge the support of NRL and ONR, and the support of the DOD HPCMPO CHSSI program in developing the TBMD software 19. We thank J.L. Feldman, M. Fornari, D.A. Papaconstantopoulos, and M.J. Mehl for helpful suggestions.