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 HfO x and SiN x gated devices suffered from a huge negative threshold voltage ( V th ) 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 V 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.