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

摘要

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 mu(TRMC), diffusion-induced mobility mu(DTRMC) and field effect mobility mu(FE). At high carrier density, the dependence of the TRMC signal on carrier density is sublinear, with slope gamma, indicating dominance of shallow trap recombinations. The decay of the signal shows two slopes tau(1) and tau(2). From the analysis of mu(TRMC), mu(DTRMC), mu(FE), gamma, tau(1) and tau(2) 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. (C) 2004 Elsevier B.V. All rights reserved.