Sol-gel derived Ga-Ln-Zn-O semiconductor layers for solution-processed thin-film transistors

We have prepared a solution processed oxide semiconductor layer for thin-film transistors. The oxide semiconductor thin-films were prepared by spin coating a sol-gel precursor solution based on Ga and In-co-doped ZnO (GIZO). The sol-gel-derived GIZO films were uniform and have smooth surface morphology (rms. roughness ∼0.7 nm). The device performance of the solution-processed thin-film transistors was analyzed as a function of the doping concentration and the annealing temperature. The transistors annealed at 450 °C showed clear switching behavior and output characteristic with relatively high field effect mobility (∼0.1 cm²/V·s) and low threshold voltage (∼5.4 V). Even when annealed at 300 °C, they showed reasonable field effect mobility (∼0.03 cm²/V·s) and a lower threshold voltage (∼-0.2 V). Our findings demonstrate the feasibility of using sol-gel-based oxide semiconductor transistors for successful application to cost-effective and mass-producible display and optoelectronic devices with enhanced device performance.