Improved Thin-Film Transistor Performance of Low-Temperature, Solution-Processed Indium Oxide by Controlling Solution Temperature

In this study, we achieved a low-temperature, high performance thin-film transistor by controlling solution temperature. Indium nitrate hydrates were dissolved in DI water and vigorously stirred for 6 hours maintaining two different solution temperatures: 0-4 degrees C and 25 degrees C. Then, the indium nitrate solutions with different solution temperatures were spin-coated with a spin speed of 4000 rpm for 30 s. After that, the coated films were annealed at 200 degrees C for 4 hours. Finally, 50-nm thick aluminum was thermally deposited to form source/drain electrodes. The results showed that the XPS O 1s spectrum of the film using the cold solution exhibits a higher metal-oxide lattice peak than that using the room temperature solution. Furthermore, the device performance of the InOx thin-film transistor (TFT) with the ice bath stirred solution was better than that with the room-temperature stirred solution. The mobility of the InOx TFT annealed at 200 degrees C with the ice bath stirred solution and the room temperature stirred solution was measured to be 0.94 and 0.66 cm2/Vs, respectively.