Creation of interface states between SiO2 and a-Si:H in a-Si:H thin film transistors by bias-stress

Abstract The bias-stress effects on hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) with a single-layered SiO 2 gate insulator were studied. The state density in the gap of a-Si:H for the a-Si:H TFT with N 2 plasma treated SiO 2 gate insulator is not changed by positive or negative bias-stress. On the other hand, the density of states in the gap of a-Si:H for the a-Si:H TFT with H 2 plasma treated SiO 2 gate insulator is greatly increased by positive or negative bias-stress. These experimental results demonstrate that the bulk density of a-Si:H is not changed even after long time bias-stress for the a-Si:H TFTs. The bias induced changes in a-Si:H TFTs are due to the changes in the interface state density between a-Si:H and a gate insulator.