Controlling instabilities of hydrogenerated a-Si:H TFT under bias temperature stressing

The hydrogenerated amorphous silicon a-Si:H thin film transistors TFT with silicon nitride as a gate insulator have been stressed with independently varying gate (V_g), source (V_s), and gate-source (V _gs) bias voltage in order to elucidate the instability mechanism and suggest the new a-Si:H TFT structure. It was found that there was dependency of threshold voltage shift not only on V_gs, but also on V_g and V_s, which had not ever been reported. Its shift amount increased with increasing V_s and/or V_g. In this reports, we suggested the new TFT device structure to eliminate the dependency of Vth shift on V_g and V_s and found that with the new suggested TFT structure, the Vth shift controlling factor can only be V_gs.