The Influence of Oxygen High-Pressure Annealing on the Performance and Bias Instability of Amorphous Ge–In–Ga–O Thin-Film Transistors

The effects of oxygen high-pressure annealing (O₂ HPA) on the performance and instability of amorphous Ge-In-Ga-O (a-GIGO) thin-film transistors (TFTs) were examined. The TFTs with HPA under 30 atm O₂ ambient exhibited consistently better stability against the applied temperature stress and positive gate bias stress. We demonstrate that the superior stability of the HPA-treated device can be correlated with the evolution of electronic structure in a-GIGO thin films, as measured by spectroscopic ellipsometry, which reveals the significantly reduced band edge states below the conduction band by the O₂ HPA treatment. Based on the Meyer-Neldel rule, the total density of subgap states energy distribution, including the interfacial and semiconductor bulk trap densities, was also extracted and compared, which can support the experimental observation.