Application of ultrasonic sprayed zirconium oxide dielectric in zinc tin oxide-based thin film transistor

Abstract

Solution processing of metal oxides has been the focal point of interest for many researchers mainly because of the cost effectiveness and improved properties of metal oxides. However, achieving uniform and high-quality film deposition has been a recurring challenge using various wet-chemical techniques. Herein, we report a fully solution-based fabrication process exploiting both the ultrasonic spray pyrolysis (USP) and spin coating techniques owing to their simplicity, high degree of freedom for mixing metal oxide precursor salt, and larger area deposition. An amorphous zirconium oxide (ZrO_x) dielectric and zinc tin oxide (ZTO) semiconductor were deposited, respectively. The dielectric characteristics of the ZrO_x thin films were accessed by fabricating MIS-devices for the samples deposited at 200 °C and 400 °C, which exhibited a capacitance of 0.35 and 0.67 μF cm⁻² at 100 kHz and relative permittivity of 8.5 and 22.7, respectively. The ZrO_x thin film was then integrated as the gate dielectric layer in ZTO solution-processed thin film transistors, exhibiting a high electrical performance with low hysteresis (−0.18 V), high on/off current ratio of 10⁶ orders of magnitude, saturation mobility of 4.6 cm² V s⁻¹, subthreshold slope of 0.25 V dec⁻¹, and operating at a low voltage window of 3 V. Based on these results, the as-fabricated ZTO/ZrO_x TFT opens the potential application of solution-processed transistors for low-cost electronic devices.