Effect of vacuum annealing on indium tin oxide transistor with nanometer-thin channel

In recent times, nanometer-thin semiconductors have garnered significant attention for their potential use as the channel materials in next-generation transistors. This interest arises from their improved device electrostatics and reduced channel length. In this study, we employed ultrathin indium tin oxide (ITO) films, measuring just 4 nm in thickness, as the channel layer in a back-gated transistor. We conducted a systematic investigation into the impact of different vacuum annealing temperatures and durations on the electrical properties of these ITO transistors. Our findings revealed that an annealing temperature of 190 °C produced improved electrical characteristics, including a high field-effect mobility of 43.6 cm2/V s, a low threshold voltage (Vth) of’ 1.1 V, and a high on/off current ratio of 1.26 × 107. Further optimization to the vacuum annealing time resulted in an even higher field-effect mobility of 61 cm2/Vs. Characterization using X-ray photoelectron spectroscopy suggested that the improved performance may be attributed to changes in oxygen vacancies within the ITO films. These findings hold significant promise for enhancing the electrical performance of ITO field-effect transistors with nanometer-thin channels.