Localization crossover and phase coherent electron transport in a-InGaZnO4 thin films

Abstract

Electrical and magnetotransport properties have been studied on pulsed laser deposition grown amorphous InGaZnO4 thin films exhibiting different disorder. A crossover from strong to weak localization was observed as disorder (quantified by a parameter kfl) decreases. The sample with kfl value 0.04 showed strong localization behavior whereas for the sample with kfl > 1, electron transport is governed by weak localization. The samples with kfl > 1 showed negative magnetoresistance (MR) because of the suppression of weak localization. From the MR study, we estimated the phase coherence length which scales with temperature as T−3∕4. The maximum phase coherence length was found to be 130 nm at 5 K for the sample with kfl = 1.71 and this can significantly influence the spintronic research in amorphous semiconductors.