Room Temperature Processed ZnO Thin Film Transistors Grown by Magnetron Sputtering Using Zirconium Oxide Gate Dielectric

A room temperature-processed ZnO thin film transistors (TFT) with zirconium oxide (ZrO₂) are demonstrated as a gate dielectric, fabricated by dc magnetron sputtering. The oxygen flow rate dependence of ZrO₂ thin films on the optical, structural, and electrical properties is investigated. Nanocrystalline ZrO₂ films with a grain size of 6.2–16.8 nm are obtained at room temperature and grain size is found to be a function of oxygen flow rate during deposition. The electrical characterization of the gate dielectric is carried out using the device structure Al-ZrO₂-Al. The leakage properties and dielectric constants are computed for the gate dielectric grown at different oxygen flow rates. Further, bottom gate staggered ZnO thin film transistors are fabricated with the configuration glass/Al/ZrO₂/ZnO/Al and the devices exhibit a field effect mobility of ≈43 cm² V⁻¹ s⁻¹, a low operating voltage of 1.5 V and on/off ratio of 10³. This work could lead to the possibility of low operating voltage TFTs for the next generation display technologies.