Influence of effective channel length in self-aligned coplanar amorphous-indium-gallium-zinc-oxide thin-film transistors with different annealing temperatures

Electrical characteristics of self-aligned coplanar amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) were investigated for different annealing temperatures. The field-effect mobility of the a-IGZO TFTs increased with the annealing temperature, in particular, for a small channel length. The effective channel length (Leff) of the a-IGZO TFTs was extracted using the transmission line method. The decrease in Leff significantly depended on the annealing temperature, due to the hydrogen diffusion into the a-IGZO channel region. The intrinsic mobility calculated from the channel resistance of the a-IGZO TFTs was in good agreement with the mobility corrected by Leff.