Zinc tin oxide thin film transistor sensor

A thin film transistor (TFT) using zinc tin oxide (ZTO), deposited from solution, as the active material is demonstrated. A sol–gel method is used to deposit the film, followed by post-deposition annealing at the temperatures from 400 to 600 °C. The field-effect mobility is found to be dependent on post-annealing temperature and becomes as high as 6 cm2 V−1 s−1 when annealed at 600 °C. The presence of interfacial traps and the surface morphology are studied using capacitance–voltage (C–V) measurement and atomic force microscopy (AFM), respectively, and are likely to be responsible for the annealing temperature-dependent mobility. The transistor is employed as a chemical vapor sensor, operating at room temperature. The sensor performance is optimized by controlling the post-annealing temperature. A considerable increase in drain current is observed in the film corresponding to annealing temperature range 400–500 °C upon delivering polar chemical analytes. The high chemical stability of such inorganic semiconducting oxides makes this a promising approach for developing chemical sensors.