Recovery characteristics of threshold voltage degradation for hydrogenated amorphous silicon thin-film transistors under DC bias stresses

The recovery characteristics of threshold voltage (Vth) for the hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) stressed under the DC bias conditions are investigated. No matter what the positive or negative gate biased stresses, there are recovery phenomena existing in the Vth degradation. The larger the magnitude of the stress voltage is, the larger the amount of Vth recovery is. Owing to the lower energy level of the hole trapping center within silicon nitride film than that of an electron, the recovery amount of Vth for the a-Si:H TFTs stressed at negative gate biased stress is larger than those stressed at positive gate biased stress.