Fractional composition of large crystallite grains: A unique microstructural parameter to explain conduction behavior in single phase undoped microcrystalline silicon

We have studied the dark conductivity of a broad microstructural range of plasma deposited single phase undoped microcrystalline silicon (μc-Si:H) films in a wide temperature range (15-450 K) to identify the possible transport mechanisms and the interrelationship between film microstructure and electrical transport behavior. Different conduction behaviors seen in films with different microstructures are explained in the context of underlying transport mechanisms and microstructural features, for above and below room temperature measurements. Our microstructural studies have shown that different ranges of the percentage volume fraction of the constituent large crystallite grains (Fcl) of the μc-Si:H films correspond to characteristically different and specific microstructures, irrespective of deposition conditions and thicknesses. Our electrical transport studies demonstrate that each type of μc-Si:H material having a different range of Fcl shows different electrical transport behaviors.