Influence of Tungsten Doping on the Performance of Indium–Zinc–Oxide Thin-Film Transistors

Thin-film transistors (TFTs) with amorphous indium-zinc-tungsten-oxide (a-IZWO) channel layer and aluminum oxide gate insulator were prepared by radio-frequency magnetron sputtering. It was found that tungsten doping ratios had a significant influence on the performance of the TFTs, and the tungsten incorporation acted as an oxygen vacancy suppressor in the IZWO thin film. The X-ray photoelectron spectroscopy of the a-IZWO thin film showed that the O1s peak associating with the oxygen-deficient regions decreased as the tungsten ratio increased. At tungsten molar ratio of 6.2%, the optimized a-IZWO-TFTs with the saturation mobility of 11.1 cm²/Vs, current ON/OFF ratio of ~10⁷, and subthreshold swing of 0.31 V/decade was obtained.