Carrier dynamics at surface and interface in hydrogenated amorphous silicon observed by the transient grating method

Carrier dynamics at a free surface and an interface in a glow discharge hydrogenated amorphous silicon (a:Si:H) film were observed by a transient grating method. The diffusion coefficients and lifetimes at the surface and in the bulk were determined separately by exciting carriers by selecting the wavelength of the excitation light. The diffusion coefficients and lifetimes in the bulk, at the surface and interfaces decreased in the following order: bulk, a:Si:H free surface, a-Si:H/substrate interface, a-Si C:H/a-Si:H interface.