Solution-deposited Zr-doped AlO_x gate dielectrics enabling high-performance flexible transparent thin film transistors

Although high dielectric constant (k) oxide thin film has been considered as a key element for high performance and low-voltage driven thin-film transistors (TFTs), there are no solution processable high-k oxide dielectrics that satisfy the stringent requirements of low-temperature processability, mechanical flexibility, and good TFT performance. Here, we demonstrate that the incorporation of a zirconium component that has strong bonding to oxygen enables a significant reduction in the processing temperature for soluble alumina dielectrics to as low as 250 °C. Based on these Zr-AlO_x films, high performance, low operational voltage, flexible TFTs are achieved. Flexible TFTs operate well under a gate bias of 5 V, exhibiting a high saturation mobility of 51 cm² V^-1 s^-1, an on/off current ratio of 10⁴, and a low threshold voltage of 1.2 V with good mechanical flexibility. This is the first study demonstrating the mechanical flexibility of all-oxide soluble high-k dielectric-semiconductor-based TFTs with an emphasis on the influence of annealing temperature on the solution-deposited high-k oxide dielectric characteristics.