Optical gaps of ab initio generated random networks for a-SiNx alloys

We report optical gaps for ab initio generated random networks of silicon-nitrogen alloys, a-SiNx, for thirteen values of x from 0 to x=1.29, a nearly stoichiometric composition. The random networks were constructed by amorphizing 64-atom periodically-continued diamond-like cells containing silicon and nitrogen, with a new thermal process and a Harris-functional based molecular dynamics code in the local density approximation. The electron energy levels were then calculated and the optical gaps obtained using a Tauc-like procedure that is not sensitive to gap states and band tails. Our results agree with experiment. (C) 2002 American Institute of Physics.