Identical Off-state Current Raise Induced by Photo-induced Schottky Barrier Lowering in a-InGaZnO4 Thin Film Transistors

Abstract

This work studies the mechanism of identical photoinduced leakage current in a-InGaZnO4 thin film transistors during reverse gate voltage sweep. There is the identical off-state current with the reverse sweep under UV light irradiation, and the photocurrent for UV light exposure region near the source electrode is more significant than that near the drain electrode, which is different from photocurrent mechanism of low temperature polysilicon TFTs. This is because the photo-generated electrons increase the carrier concentration in a-InGaZnO4 bulk, causing the reduced depletion width of the active layer. Therefore, the back channel of active layer is out of gate control.