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

Abstract

The projection operator method developed in I to discuss the dangling bond states is used to give a rigorous argument on the energy bounds for the electronic states of hydrogenated bonds in amorphous silicon. Two types of model for a-Si: H are considered: In the first model, each dangling bond is terminated by connecting single hydrogen atom (SiH model), and in the second model a broken bond at random is filled by two hydrogen atoms (SiHHSi model). For both models, it is concluded from analysis of energy bounds that the energy gap is always increased due to the passivation of dangling bond by hydrogenation.