Instability in a-Si:H Thin-Film Transistor: A New Method to Discriminate Between Charge Injection and Defect Creation

Abstract

ABSTRACTIn the present work, in order to discriminate the main source of instability in a-Si:H TFTs, the determination of both threshold voltage and flat-band voltage has been performed after bias-stressing the devices with different gate voltages and at different temperatures. Flat-band voltage was determined by the space-charge photomodulation technique. From the close correlation observed between the two quantities, we conclude that the predominant instability mechanism is represented by change in the gate insulator charge at and near the semiconductor/insulator interface.