Effect of Zn Doping on an Inkjet-Printed Metal Oxide Thin-Film Transistor at Low Temperature of 200 °C

摘要

Amorphous oxide semiconductors have attracted much attention due to their good electrical properties with wide band gaps and low cost process, which are used as backplanes for displays. However, there are some issues regarding low temperature process with high mobility and printing capability. The inkjet method is an attractive technology for high resolution printing with drop-on-demand patterning. Doping is a useful technology to control semiconductor properties. We prepared zinc-doped metal-oxide semiconductors using the inkjet-printing technique at a low temperature of 200 °C. The In_2O_3 formulation with various doping concentrations of zinc during the inkjet process was thoroughly investigated. For the case of In_2O_3 TFT, the electrical properties were influenced by the concentration of zinc. The lower zinc concentration exhibited better TFT electrical properties due to the suitable suppression of carriers. The threshold voltage of the metal oxide TFT was negatively shifted with zinc doping concentrations. The 0.025M Zn doped In_2O_3 TFT showed the best performance, which was similar to In_2O_3 TFT, and exhibited a more positively shifted threshold voltage under hysteresis and positive bias stress. When the doping concentration of zinc was 0.025 M, the TFT demonstrated a mobility of 1.80 cm~2/Vs, an on-to-off current ratio of 1.49 X 107, a threshold voltage of -3.26 V and a subthreshold slope of 0.3 V dec~(-1).