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

Abstract

This study examined the effect of gate dielectric materials on the light-induced bias instability of Hf–In–Zn–O (HIZO) transistor. The ${\text{HfO}}_x$ and ${\text{SiN}}_x$ gated devices suffered from a huge negative threshold voltage $\left({\text{V}}_{\text{th}}\right)$ shift $\left(>11\text{V}\right)$ during the application of negative-bias-thermal illumination stress for 3 h. In contrast, the HIZO transistor exhibited much better stability $\left(<2.0\text{V}\right)$ in terms of ${\text{V}}_{\text{th}}$ 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.