Crossover from Hopping to Diffusive Transport with Increasing Gate Voltage in Poly-Si MOS Inversion Layer

Variation in the temperature dependence of the resistance and magnetic-field dependence of negative magnetoresistance (MR) with increasing gate voltage has been studied on an n-channel poly-Si MOS inversion layer. We find a crossover from strongly-localized (hopping) to weakly-localized (diffusive) regime in two dimensions around the sheet resistance of approximate to 6 k Omega with increasing gate voltage. In both regimes, the negative MR due to orbital motion is observed and explained by the quantum interference effects.