Influence of Post-UV/Ozone Treatment of Ultrasonic-Sprayed Zirconium Oxide Dielectric Films for a Low-Temperature Oxide Thin Film Transistor

摘要

Solution-processed metal oxides require a great deal of thermal budget in order to achieve the desired film properties. Here, we show that the deposition temperature of sprayed zirconium oxide (ZrO ) thin film can be lowered by exposing the film surface to an ultraviolet (UV) ozone treatment at room temperature. Atomic force microscopy reveals a smooth and uniform film with the root mean square roughness reduced from ~ 0.63 nm (UVO-O) to ~ 0.28 nm (UVO-120) in the UV–ozone treated ZrO films. X-ray photoelectron spectroscopy analysis indicates the formation of a Zr–O network on the surface film, and oxygen vacancy is reduced in the ZrO lattice by increasing the UV–ozone treatment time. The leakage current density in Al/ZrOx/p-Si structure was reduced by three orders of magnitude by increasing the UV-ozone exposure time, while the capacitance was in the range 290–266 nF/cm , corresponding to a relative permittivity (k) in the range 5.8–6.6 at 1 kHz. An indium gallium zinc oxide (IGZO)-based thin film transistor, employing a UV-treated ZrO gate dielectric deposited at 200 °C, exhibits negligible hysteresis, an I /I ratio of 10 , a saturation mobility of 8.4 cm V S , a subthreshold slope of 0.21 V.dec , and a V of 0.02 V. These results demonstrate the potentiality of low-temperature sprayed amorphous ZrO to be applied as a dielectric in flexible and low-power-consumption oxide electronics.