The density of localized states in hydrogenated amorphous material was studied by using quasistatic capacitance techniques. Calculations which were based upon the defect-pool model showed that changes in the quasi-static capacitance after bias annealing reflected changes in the density of dangling-bond states which were predicted by the model, and which were sensitive to the defect-pool parameters. A comparison of theoretical and experimental curves strongly supported the defect-pool model, and values of the model parameters were deduced. It was shown that the predominant phenomenon during bias annealing was the creation of defects in the lower part of the gap in amorphous hydrogenated material. Bias annealing under hole accumulation conditions revealed the creation of defects in the upper part of the gap of amorphous hydrogenated material.

Theoretical and experimental study of the quasi-static capacitance of metal-insulator hydrogenated amorphous silicon structures J.P.Kleider, F.Dayoub: Physical Review B, 1998, 58[16], 10401-14