Effect of channel layer thickness on characteristics and stability of amorphous hafnium-indium-zinc oxide thin film transistors

We investigated the channel layer thickness dependence of the characteristics and stability in amorphous hafnium indium zinc-oxide (HIZO) thin film transistors (TFTs). HIZO TFTs were prepared with various channel thicknesses from 400 to 700 Å. In HIZO TFTs, carrier concentration is considerably high, which leads to channel layer thickness dependence. The threshold voltages of TFTs negatively shifted as the channel thickness increased. The threshold voltage shift at a high temperature is more severe in TFTs with thicker channel layers. The channel thickness dependence of the bias stability of HIZO TFTs is closely related to the back interface, rather than the bulk state.