Integration of bandgap-engineered double-stacked channel layers with nitrogen doping for high-performance InGaO TFTs

High-performance indium-gallium oxide (IGO) thin film transistors (TFTs) with a double-stacked channel layer (DSCL) were obtained by the in-situ nitrogen doping technique. By means of their distinctive feature of bandgap narrowing, devices with an IGO/IGO:N double-stacked channel showed superior electrical characteristics (μFE = 25 cm2/V s and ION/IOFF > 108) than those with a single channel layer. Moreover, owing to the reduced oxygen vacancies, the bias stability was significantly improved. Through X-ray photoelectron spectroscopy analysis, we optimized the model of bandgap engineering. It not only provides an explicit principle for the design of the DSCL configuration but also facilitates the manufacture of high-quality passivation-free TFTs for practical applications.