Laser spectroscopic study of photoinduced picosecond processes in amorphous and polycrystalline silicon films

Abstract

Picosecond photoinduced absorption and reflection curves of hydrogenated amorphous silicon (a-Si:H), dehydrogenated amorphous silicon (a-Si) and polycrystalline silicon (p-Si) samples have been recorded at charge carrier densities of ∼ 10 20 cm −3. The temporal decays of the photoinduced changes in the real and imaginary parts of the refractive index have been computed. The results suggest that the relaxation of the photogenerated carriers is dominated by a monomolecular recombination in a-Si:H and a-Si, whereas the relaxation is non-exponential in p-Si where it may be controlled by the diffusion of the carriers to the grain boundaries.