The impact of gate dielectric materials on the light-induced bias instability in Hf–In–Zn–O thin film transistor

This study examined the effect of gate dielectric materials on the light-induced bias instability of Hf–In–Zn–O (HIZO) transistor. The HfOx and SiNx gated devices suffered from a huge negative threshold voltage (Vth) shift (11 V) during the application of negative-bias-thermal illumination stress for 3 h. In contrast, the HIZO transistor exhibited much better stability (2.0 V) in terms of Vth movement under identical stress conditions. Based on the experimental results, we propose a plausible degradation model for the trapping of the photocreated hole carrier either at the channel/gate dielectric or dielectric bulk layer.