Hopping transport in band-tail of grain boundaries in poly-Si TFTs

The low-temperature transport in high-mobility poly-Si TFT fabricated using laser annealing of amorphous Si film has been studied in the two-dimensional variable-range hopping (VRH) regime near the crossover between the weak and strong localization. The resistance follows the Efros-Shklovskii (ES) VRH as In R α T−1/2 below ∼ 20 K in the presence of a Coulomb gap in the density of states. The negative magnetoresistance ΔRR varies below ∼ 4 K as ∼ T−3/2B2 in low-magnetic fields and as ∼T−3/4B in moderate fields both in agreement with the theoretical predictions based on quantum interference.