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Highlights • A unified explanation is proposed to consistently explain the two-step degradation of a-IGZO TFTs under DC PBTI stress without or with different stress V ds. • For PBTI stress without stress V ds , the initial negative V th shift is believed to be induced by donor-like defect states corresponding to H 2 O molecule and intrinsic defects. • For PBTI stress with stress V ds , the negative shift is believed to be induced by donor-like defect states corresponding to oxygen vacancies. The gate-bias-induced electron trapping mechanism is responsible for the positive V th shift. Abstract A unified explanation is proposed to consistently explain the two-step degradation of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) under DC positive bias temperature instability (PBTI) stress without or with different drain stress voltages (V ds). For PBTI stress without stress V ds , this initial negative V th shift is believed to be induced by donor-like defect states corresponding to H 2 O molecule and intrinsic defects, while for PBTI stress with stress V ds , the negative shift is believed to be induced by donor-like defect states corresponding to oxygen vacancies. The gate-bias-induced electron trapping mechanism is responsible for positive V th shift. These transitions from negative to positive V th shift are resulted from the competition between the donor-like states creation and electron trapping. [ABSTRACT FROM AUTHOR]

Mg-doped InZnO (MIZO) films were prepared by sol-gel method, and bottom-gate structured thin film transistors (TFTs) were prepared by using the MIZO films. Oxygen and argon (Ar) plasma treatments were carried out on the film and TFTs. The X-ray photoelectron spectroscopy (XPS) results show that both Ar and oxygen etching can increase the oxygen deficiencies, which effectively increase the content of carrier concentration in MIZO films. After both kinds of plasma treatment, the field effect mobility of the MIZO TFTs is greatly improved and the on/off current ratio increases two orders of magnitude. [ABSTRACT FROM AUTHOR]

• Positive charges from H 2 O molecule induced the parasitic current path, resulting in anomalous hump in subthreshold region at elevated temperature, which disappeared after N 2 annealing. • Hump still existed under PBS, while weakened hump were observed under NBS due to positive charges trapping. In this work, we investigated an anomalous hump in the bottom-gate amorphous-InGaZnO thin-film transistors. The hump in the subthreshold region appeared at elevated temperature and disappeared after N 2 atmosphere annealing. The anomalous hump phenomenon is attributed to the existence of both main current path composed by electron and parasitic current path induced by positive charges formed by adsorbed H 2 O molecules. With the increase of the testing temperature, the hump effect becomes significant since the formation of positive charges is strengthened by heat. This hump can be weakened by negative bias temperature instability stress at high temperature due to the charge-trapping mechanism. [ABSTRACT FROM AUTHOR]