High-performance Zinc-Tin-Oxide thin film transistors based on environment friendly solution process

Abstract

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 °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 TFTs showed obvious dependence on annealing temperature. The ZTO TFTs annealed at 500 °C showed a high carrier mobility of 5.9 cm2/V, high on/off current ratio (Ion/off) of 106-107, and threshold voltage (Vth) 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 cm2/V and Ion/off of 105-106 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.