Different values were obtained for dangling-bond densities as evaluated by applying the electron spin resonance and constant photo-current methods to undoped and N-doped hydrogenated amorphous Si (a-Si:H) films of various thickness during light-soaking using white and red light. The origin of the difference was explained by taking account of the inhomogeneous distribution of photo-created dangling-bonds across the film

thickness, caused by the penetration depth of the light to be less than the film thickness. The main cause of the difference in undoped a-Si:H was found to be the inhomogeneous distribution of photo-created dangling bonds, whereas the main cause in N-doped a-Si:H was found to be the presence of a large number of negatively charged dangling bonds inactive to electron spin resonance. The presence of a thin near-surface layer with a high density of dangling bonds, invisible to the constant photo-current method, also contributed to the difference between electron spin resonance and constant photo-current method dangling-bond densities in both undoped and N-doped a-Si:H.

Comparative Study of Defect Densities Evaluated by Electron Spin Resonance and Constant Photocurrent Method in Undoped and N-Doped Hydrogenated Amorphous Silicon. T.Shimizu, M.Shimada, M.Kumeda: Japanese Journal of Applied Physics - 1, 2002, 41[5A], 2829-33