Improved Stability of Pr-Doped Amorphous InGaZnO4 Thin-Film Transistors under Negative Bias Illumination Stress

Negative bias illumination stress (NBIS) instability is an important issue to overcome for the application of amorphous InGaZnO4 (a-IGZO) thin-film transistors (TFTs) in flat-panel displays. In this work, TFTs based on praseodymium (Pr)-doped a-IGZO were fabricated, and their NBIS stability at different temperatures was characterized. The transfer curve shifts in the negative gate bias direction under NBIS, and the magnitude of the shift increases significantly at elevated temperatures even with a weak illumination intensity. Benefiting from Pr doping, the oxygen vacancies in the channel a-IGZO can be reduced for TFTs with a metal cover layer after annealing in an oxygen atmosphere. Thus, significantly improved NBIS stability of a-IGZO TFTs at both room temperature and elevated temperatures is demonstrated.