Characterizing and Modelling of the BTI Reliability in IGZO-TFT using Light-assisted I-V Spectroscopy

The sub-gap Density-of-State (DoS) in IGZO thin-film transistors (TFT) is systematically investigated using a newly developed Light-assisted I-V Spectroscopy (LaIVs). The technique quantifies the sub-gap DoS of pristine IGZO device and how they evolve with the electrical stress. By combining LaIVs with a model of the entire I-V, charge trapping in the gate-dielectric defects and sub-gap DoS changes during Positive Bias Temperature Instability (PBTI) are decoupled. Their time kinetics and voltage acceleration factors are extracted, allowing to project the I-V degradations to any stress time and voltages.