Electronic transport in hydrogenated microcrystalline silicon: similarities with amorphous silicon

Undoped hydrogenated microcrystalline silicon (mu c-Si:H) layers were grown by the very high frequency glow discharge (VHF-GD) technique under various deposition conditions. The electronic transport properties under illuminat ion were investigated by means of steady-state photoconductivity and steady -state photocarrier grating methods. Similarly to hydrogenated amorphous si licon (a-Si:H), power law dependencies as a function of the generation rate are observed for the photoconductivity, for the ambipolar diffusion length , and for the parameter b (indicating the Fermi level). For mu c-Si:H, as f or a-Si:H, nearly constant product of (mobility x recombination time) of ma jority and minority carriers is observed as a function of the parameter b. Based on these similarities, we assume that the electronic transport model developed for a-Si:H remains valid for mu c-Si:H. (C) 2000 Elsevier Science B.V. All rights reserved.