Study of transport, trapping and recombination mechanisms in microcrystalline silicon by transient photoconductivity

We have studied different sets of microcrystalline silicon films deposited by PECVD and plasma assisted HWCVD at different thicknesses and microstructures. Measurements by time-resolved microwave conductivity (TRMC) give a mobility μ_TRMC, diffusion-induced mobility μ_DTRMC and field effect mobility μ_FE. At high carrier density, the dependence of the TRMC signal on carrier density is sublinear, with slope γ, indicating dominance of shallow trap recombinations. The decay of the signal shows two slopes τ₁ and τ₂. From the analysis of μ_TRMC, μ_DTRMC, μ_FE, γ, τ₁ and τ₂ for different samples, we discuss the contribution of grains, grain boundaries, and column boundaries to the mobility, to the fast recombination process, and to the lifetime.