Impact of Ti doping in Sm₂O₃ dielectric on electrical characteristics of a-InGaZnO thin-film transistors

We investigated the impact of Ti doping in the Sm₂O₃ dielectric on the electrical stress-induced instability in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). With increasing stress time in a-IGZO TFT devices, a small initial positive shift followed by a negative shift of threshold voltage is characterized in the Sm ₂O₃ dielectric, whereas only positive shift of threshold voltage is observed for Ti-doped Sm₂O₃ dielectric. The positive shift of the threshold voltage can be explained by charge trapping in the Sm₂O₃ film and/or the Sm₂O₃/IGZO interfaces, while the negative shift of threshold voltage is probably due to the extra charges from the IGZO channel by self-heating effect.