Photonic Cured Metal Oxides for Low-Cost, High-Performance, LowVoltage, Flexible, and Transparent Thin-Film Transistors

Flash light-based photonic curing has recently emerged as a promising technique for low-cost and ultrafast production of flexible electronics. In this work, we demonstrate photonic curing-based low-cost fabrication of ZrO2-based high-k dielectric and ZnO-based semiconducting layers for low-voltage, high-performance, flexible, and transparent thin-film transistors (TFTs). Such metal oxide-based devices are extremely important to realize next-generation technologies with high power efficiency, optical transparency,mecahnical flexibility, high reliability, and environmental stability. In the current work, photonic cured ZrO2 and ZnO layers were obtained by exposing their spin-coated precursor solutions to the high-energy pulsed light of a xenon flash lamp. The numbers of applied pulses were varied for optimization. Hence, the optimally cured ZrO2 film exhibited excellent dielectric property with high areal capacitance of similar to 485 nFcm(-2), low leakage current density of 10(-4) A cm(-2), and high breakdown strength of similar to 2.3 MV cm(-1) which further enabled the low-voltage operation (< 3 V) for the fabricated TFTs. On the other hand, the optimally cured ZnO layer resulted in the high performance for the TFTs with field-effect mobility of 3.4 +/- 0.1 cm(2) V-1 s(-1), on-off ratio of 3.3 +/- 0.8 x 10(5), and threshold voltage of 0.8 +/- 0.03 V. The mechanical flexibility of these devices was demonstrated by showing their operational stability under mechancial bending and after continuous bending cycles. These devices also exhibited optical transparency up to 80% in the visible wavelength range. To explain the behavior of these photonic cured layers and devices under different process conditions, several microscopic and spectroscopic studies were performed. Finally, the ultraviolet-visible absorption spectroscopy and a finite element simulation study also showed the viability of photonic curing to successfully fabricate solution-derived ZnO and ZrO2 layers on a flexible substrate.