Effect of processing temperature on the structural, electronic and electrical properties of solution-processed amorphous Ge-In-Sn-O thin-film transistors

Abstract

We report a novel GeInSnOx (GeITO) thin-film transistor (TFT) synthesized by a solution process, utilizing Ge as a charge carrier suppressor and amorphization-promoter, and the dependence of its microstructure, electronic structure and electrical properties on sintering temperature. The amorphous structure was maintained regardless of the sintering temperature. As the sintering temperature increased, the amount of oxygen vacancies increased and GeO2 bonds transformed into GeO bonds near the film surface above 400 degrees C. In addition, the In 5sp/Sn 5sp states appeared to act as the dominant electron source in the GeITO channel layers with increasing sintering temperature. These behaviours influenced TFT performances: the saturation mobility was increased from 0.004 to 6.4 cm(2) V-1 s(-1), while the threshold voltage was shifted in the negative direction by increasing the sintering temperature, which demonstrates the high sensitivity of the solution-deposited GeITO to the processing temperature.