Effect of Gd3+ Doping on Sol–Gel Prepared Y2O3 Films as Gate Insulators for Oxide Thin Film Transistors

The relationships between the microstructure and the dielectric properties of sol–gel prepared Y2O3 films with various Gd3+ doping were systematically investigated. Robust solution processed lanthanide films, (Y1−xGdx)2O3 (0 < x ≤ 0.5), are demonstrated as high-k gate insulators for low voltage-driven oxide thin film transistors and their optimized composition is presented. With the proper amount of Gd3+ doping, the corresponding thin film insulators exhibit low leakage current with increased dielectric constant. The resultant Zn–Sn–O/(Y, Gd)2O3 TFT exhibits enhanced performance, by a factor of 10.7 compared with TFTs using a SiO2 insulator, with a field-effect mobility of ~3.15 cm2V−1s−1 and an exceptionally low operating voltage <15 V.