The effect of moisture on the photon-enhanced negative bias thermal instability in Ga-In-Zn-O thin film transistors

We investigated the impact of photon irradiation on the stability of gallium-indium-zinc oxide (GIZO) thin film transistors. The application of light on the negative bias temperature stress (NBTS) accelerated the negative displacement of the threshold voltage ( V th ) . This phenomenon can be attributed to the trapping of the photon-induced carriers into the gate dielectric/channel interface or the gate dielectric bulk. Interestingly, the negative V th shift under photon-enhanced NBTS condition worsened in relatively humid environments. It is suggested that moisture is a significant parameter that induces the degradation of bias-stressed GIZO transistors.