Transparent amorphous In-Ga-Zn-O thin film as function of various gas flows for TFT applications

Abstract

The electrical and optical properties of amorphous indium gallium zinc oxide (a-IGZO) films, which can be used as a channel layer, deposited by radio frequency (rf) magnetron sputtering system at room temperature (RT), were investigated as function of various gas flows. The optical transmittance of films deposited under At, O(2) / Ar + O(2) and O(2) / Ar-4% H(2) + O(2) atmospheres in the visible wavelength was consistently above 90% at a wavelength of 550 nm at all gas flows, although the film deposited under Ar-4% H(2) atmosphere exhibited a transmittance of below 50%. The carrier concentration and mobility of the a-IGZO films fabricated under At and Ar-4% H(2) were observed slight decrease as a function of the flow, respectively. The thin film transistors (TFrs) with an a-IGZO channel deposited under At and Ar-4% H(2) atmosphere exhibited the following good characteristics: Vth of 0.34 V, mu(FE) of 3.6 cm(2) V(-1) s(-1), on/off ratio of 10(6), and S value of 0.04 V decade(-1). (C) 2009 Elsevier B.V. All rights reserved.