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 degrees C. The field-effect mobility is found to be dependent on post-annealing temperature and becomes as high as 6 cm(2) V-1 S-1 when annealed at 600 degrees 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 degrees C upon delivering polar chemical analytes. The high chemical stability of such inorganic semiconducting oxides makes this a promising approach for developing chemical sensors. (C) 2009 Elsevier B.V. All rights reserved.