Formation Mechanism of Solution-Processed Nanocrystalline InGaZnO Thin Film as Active Channel Layer in Thin-Film Transistor

Solution-processed indium gallium zinc oxide (IGZO) thin films as an active channel layer in thin-film transistors (TFTs) were successfully prepared by a spin-coating method using acetate- and nitrate-based precursors. In the range of 60-130 degrees C, indium, gallium, and zinc precursors were dissociated and then hydrolyzed to metal hydroxides. InGaZn2O5 compound was synthesized at similar to 196 degrees C and crystallized at 305-420 degrees C. A spin-coated IGZO film annealed at 450 degrees C had smooth morphology and fine grains with an average size of similar to 15 nm. In solution-processed IGZO TFTs using nanocrystalline films prepared at 450 degrees C, the on-to-off ratio, a field effect mobility, and the subthreshold swing voltage were similar to 10(6), 0.96 cm(2)/V s, and 1.39 V/decade, respectively.