Characteristics of low doped gallium-zinc oxide thin film transistors and effect of annealing under high vacuum

We report on the fabrication and electrical characteristics of thin film transistors (TFTs) based on low Ga-doped zinc oxide (GZO). Low Ga-doped (1 wt.%) ZnO thin films deposited as an active channel by radio frequency magnetron sputtering at room temperature exhibit a high transmittance (> 80%). The devices show a mobility of ~ 5.7 cm2/Vs at low operation voltage of < 5 V and a low turn-on voltage of ~ 0.5 V with a subthreshold swing of ~ 85 mV/decade. The TFT device performance is significantly affected by vacuum-level and annealing treatment, which is attributed to the chemisorption/desorption of oxygen from the surface of active channel. Low doped GZO is a type of TFT channel material that has potential for high performance, multi-functionality and easy-process.