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 be tween the weak and strong localization. The resistance follows the Efr os-Shklovskii (ES) VRH as ln R proportional to T-1/2 below similar to 20 K in the presence of a Coulomb gap in the density of states. The ne gative magnetoresistance Delta R/R varies below similar to 4 K as simi lar to (T-3/2B2) in low-magnetic fields and as similar to T-B-3/4 in m oderate fields both in agreement with the theoretical predictions base d on quantum interference.