Current Applied Physics, Vol.19, No.2, 174-181, 2019
High-performance Zinc-Tin-Oxide thin film transistors based on environment friendly solution process
Zinc-Tin-Oxide (ZTO) thin films were fabricated using a simple and eco-friendly sol-gel method and their application in thin film transistors (TFTs) was investigated. Annealing temperature has a crucial influence on the structure and electrical properties of sol-gel ZTO thin films. The ZTO thin films annealed at 300-600 degrees C revealed smooth and uniform surfaces with amorphous state, in addition, a high optical transparency over 90% of the ZTO films in the visible range was obtained. The electrical performance of ZTO TFT5 showed obvious dependence on annealing temperature. The ZTO TFTs annealed at 500 degrees C showed a high carrier mobility of 5.9 cm(2)/V, high on/off current ratio (I-on/off) of 10(6)-10(7), and threshold voltage (V-th) of 1.03 V. To demonstrate the application of sol-gel ZTO films in low-power display fields, we also fabricated ZTO TFTs with a solution-processed high-permittivity (high-k) ZrTiOx dielectric layer. The ZTO/ZrTiOx TFTs showed high mobility of 17.9 cm(2)/V and I-on/off of 10(5)-10(6) at a low operation voltage of 3 V, indicating that Indium-free ZTO thin films would be potential candidates for low cost, high performance oxide TFT devices.