Theory of Gap States in a-Si and a-Si: H I. Rigorous Energy Bounds for Dangling Bond States

Abstract

On the basis of Weaire-Thorpe model, a rigorous argument is given on the energy bounds for the electronic states of dangling bonds in amorphous silicon. Starting with the equation of motion for the amplitude of LCAO wave function derived from the Weaire-Thorpe Hamiltonian, several inequalities holding among the amplitude and model parameters are derived. Based on these inequalities, the energy bounds for the valence band, conduction band and mid gap energy band are determined. An estimate of the gap as function of dangling bond concentration is given.