Ultrafast carrier dynamics in nanocrystalline silicon - art. no. 161309

We present studies of the ultrafast dynamics of photoexcited carriers in th in-film nanocrystalline silicon materials in which the degree of crystallin ity has been systematically varied by controlling the deposition conditions . Femtosecond pump-probe measurements reveal a multicomponent response that can be understood in terms of the separate phases of the heterogeneous mat erial. We observe a 240-fs exponential relaxation process associated with i ntraband carrier relaxation in the silicon crystallites a response characte ristic of bimolecular recombination in the amorphous silicon matrix, and a long-lived component assigned to grain-boundary states.