Properties of indium zinc oxide thin films on heat withstanding plastic substrate

Abstract

We have investigated ZnO doped indium oxide (IZO) as a transparent conductive oxide (TCO) film with low resistivity and high tolerance to heat treatment deposited on a plastic substrate with high glass transition temperature (Tg), optical isotropy and dimensional stability. The resistivity of IZO with 7.5 wt % ZnO film [IZO(7.5)] is 2.9×10−4 Ω cm, which is 33% lower than that of tin doped indium oxide film (ITO) and remains unchanged even after annealing at 180 °C for 4 h. We establish by x-ray diffraction and transmission electron microscope that the structure of annealed IZO(7.5) is amorphous and by DSC that the structure starts to transform to the crystalline phase at 350 °C. The etching rate of IZO(7.5) films is almost the same as, or quicker than, that of amorphous ITO films. The durability of IZO(7.5) against the alkali solution is also good for practical use.