Dependence of optoelectronic properties of IGZO thin films deposited by RF magnetron sputtering on initial vacuum pressure

The structures and characteristics of Indium-Gallium-Zinc-Oxide(IGZO) transparent semiconducting films prepared by magnetron sputtering can be influenced by various factors. However, the role of the initial vacuum pressure is seldom investigated, especially on the photoelectric properties of amorphous IGZO films (α-IGZO films). Herein, high-quality, transparent conductive α-IGZO films were deposited by radio frequency (RF) magnetron sputtering at 200 ℃ under various initial vacuum pressures ranging from 1 × 10^–6 to 10 × 10^–6 Torr. The results revealed that increasing the initial vacuum pressure gradually enhanced the root-mean-square roughness of the films and the formation of columnar structures. At lower vacuum pressures, the carrier mobility and concentration increased due to the enhanced number of oxygen vacancies, resulting in reduced film resistivity. The lowest resistivity of 1.6 × 10^–3 Ω·cm was obtained at an initial vacuum pressure of 1 × 10^–6 Torr, with an average transmittance of 92.11%. Further decrease in the initial vacuum pressure improved the quality factor of α-IGZO films, with all prepared films showing transmittance values exceeding 90% in the visible range. Overall, vacuum pressure significantly affects the structures and photoelectric properties of α-IGZO films, deserving further exploration for the advanced preparation of α-IGZO films.