Effect of the microstructure on the electronic transport in hydrogenated microcrystalline silicon

Undoped hydrogenated amorphous silicon layers deposited at different values of very high frequency (VHF) powers and silane to hydrogen dilution ratios possess various types of microstructures. Transport and defect measurements on layers suggest that structural properties (e.g., crystallite shape and size) do not significantly affect electronic properties. The latter depend mostly on defect density and on the Fermi level. The authors therefore suggest using the ‘quality parameter' μ⁰τ⁰ for an unambiguous comparison between different μc-Si:H layers. Transport characterisation techniques in the direction perpendicular to the substrate and cell performance results corroborate the minor effect of microstructure on the bulk electronic transport properties.