Defect chemical potential and the density of states in amorphous silicon

We derive a general expression for the defect chemical potential of amphoteric silicon dangling bond states in amorphous silicon. We show that a single expression is valid, irrespective of the charge state of the dangling bond. We apply this result in a defect pool model for the formation of dangling bonds by the breaking of weak silicon-silicon bonds, with and without hydrogen motion. We calculate the resulting energy dependent density of states.