Stable and High-Performance Indium Oxide Thin-Film Transistor by Ga Doping

Research on a replacement of amorphous silicon for a thin-film transistor (TFT) and large area electronics has been driven by costly vacuum processed indium-gallium-zinc oxide (IGZO). Even though widely studied, the performances still require improvement, and a wide number of other materials have been tested. While indium-zinc oxide, IGZO, indium-zinc-tin oxide (ZTO), and ZTO have been widely investigated, gallium-doped indium oxide (IGO) has not been under highlight. Here, we report the use of simple and cost effective spin-coated IGO TFT using spin-coated AlO_x gate dielectric. We achieved high mobility over 50 cm²/Vs and high stability. The thin films are studied by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectra, atomic force microscopy, and field-effect measurements. Analyses reveal the strong dependence between crystallinity, mobility, and stability. All TFTs show excellent operation, with champion characteristics for the 10% Ga-doped InO_x, revealing a mobility of 52.6 cm²/Vs, ON/OFF ratios of 10⁸, and V_TH variation of <;0.1 V during 1 h of stress measurement.