Effects of film thickness and Sn concentration on electrical properties of solution-processed zinc tin oxide thin film transistors

Abstract

This paper investigates the effect of Sn concentration and film thickness on properties of zinc tin oxide (ZTO) thin film transistors (TFTs) fabricated using a solution process. ZTO solution was synthesized using zinc acetate dehydrate and tin chloride dehydrate dissolved in a solvent composed of 2-methoxyethanol and mono-ethanolamine. A ZTO film was obtained for an active channel on a gate oxide layer by spin-coating the solution at room temperature, drying at 300°C for 10min, and annealing at 550°C for 120min. The thickness and Sn concentration affected the material structure and electrical properties of ZTO film. The best solution processed ZTO TFT was obtained at film thickness of 35nm and Sn concentration of 30at.%. The fabricated ZTO TFT exhibited an on/off ratio of 1.88×107, a field effect mobility of 17.02cm2/Vs, a subthreshold swing of 0.77V/decade, and a threshold voltage of 5.01V.