Bias-stress stability of top-gate coplanar a-ITGZO TFTs with HfO2 and HfAlO gate dielectrics

In this study, we investigated the electrical characteristics of amorphous indium-tin-gallium-zinc-oxide thinfilm transistors (TFTs) (a-ITGZO TFTs) with HfO2 and HfAlO gate dielectrics. The mobilities of the a-ITGZO TFTs with HfO2 and HfAlO were 32.3 and 26.4 cm(2)/V &.s, respectively. The TFT with HfO2 showed a subthreshold swing (SS) of 206 mV/dec and a hysteresis window of 0.60 V, and the TFT with HfAlO showed an SS of 160 mV/dec and a hysteresis window of 0.12 V. The hysteresis windows were related to the interface trap density. The TFT with HfO2 was more vulnerable to positive bias stress; in contrast, the TFT with HfAlO operated stably even after it experienced positive and negative bias stresses for 3000 s.

Automated summary

This study investigated the electrical characteristics of amorphous indium-tin-gallium-zinc-oxide thin-film transistors (a-ITGZO TFTs) with HfO2 and HfAlO gate dielectrics. The results showed that the TFT with HfO2 was more vulnerable to positive bias stress, while the TFT with HfAlO exhibited better stability.