Process-controlled staggered ambipolar amorphous-silicon thin-filmtransistor

The results of measurements performed on amorphous-silicon thin-film transistors (TFTs) are presented and interpreted. Both unipolar and ambipolar effect TFTs are obtained in the experiments. Whether they possess unipolar or ambipolar characteristics is controlled by the interface properties between gate insulator and amorphous silicon. With the different compositions of hybrid gate insulators, the devices show different I-V characteristics. A simple method for estimating film parameters of amorphous silicon and device parameters of the TFTs is developed. The characteristic energy of an amorphous-silicon film is obtained from the slope of the ratio of saturation current to transconductance. Threshold voltages and flatband voltages of the TFTs can also be obtained using this method