Enhanced Optical and Electrical Properties of TiO2 Buffered IGZO/TiO2 Bi-Layered Films

Abstract

In and Ga doped ZnO (IGZO, 100-nm thick) thin films were deposited by radio frequency magnetron sputtering without intentional substrate heating on a bare glass substrate and a TiO2-deposited glass substrate to determine the effect of the thickness of a thin TiO2 buffer layer on the structural, optical, and electrical properties of the films. The thicknesses of the TiO2 buffer layers were 5, 10 and 15 nm, respectively. As-deposited IGZO films with a 10 nm-thick TiO2 buffer layer had an average optical transmittance of 85.0% with lower resistivity (1.83×10(-2) Ω cm) than that of IGZO single layer films. The figure of merit (FOM) reached a maximum of 1.44×10(-4) Ω-1 for IGZO/10 nm-thick TiO2 bi-layered films, which is higher than the FOM of 6.85×10(-5) Ω-1 for IGZO single layer films. Because a higher FOM value indicates better quality transparent conducting oxide (TCO) films, the IGZO/10 nm-thick TiO2 bi-layered films are likely to perform better in TCO applications than IGZO single layer films. (Received January 19, 2016; Accepted March 20, 2016)