DENSITY OF STATES OF AMORPHOUS HYDROGENATED Si

In this paper, we analyze the electronic density of state of amorphous semiconductors with a dengling bond, either unsatisfied or satisfied by a monovalent atom (H, Cl, F...) as it is now currently achieved. The electronic properties are calculated within the tight binding framework. In the simplified case of the Bethe lattice, exact formulas are obtained. We observe an isolated dangling bond state in the gap, with a weight depending on the gap width, The density of states is also obtained when an adatom is covalently attached to the dangling bond. The range of parameters required for emptying the gap is analyzed. Finally more sophisticated numerical calculations are done on a realistic hand built 500 atom model