A large discrepancy between the defect densities which were evaluated using electron spin resonance, and those found using the constant photo-current method, was investigated in amorphous hydrogenated material. Films of various thickness were soaked with both white and red light in order to increase the defect density. The defect densities in these films were then evaluated by using electron spin resonance and constant photo-current methods. The results were reproduced fairly well by using a computer simulation which took account of an inhomogeneous defect distribution across the film thickness that arose because the penetration depth of the light was smaller than the film thickness. The presence of negatively charged dangling-bonds was also found to contribute to the discrepancy, between the defect densities which were evaluated using electron spin resonance and constant photo-current methods, in the case of thin films which were soaked with red light.

Relation between Electron-Spin-Resonance and Constant-Photocurrent Method Defect Densities in Hydrogenated Amorphous Silicon. T.Shimizu, M.Shimada, H.Sugiyama, M.Kumeda: Japanese Journal of Applied Physics - 1, 2001, 40[1], 54-8