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 (T-g), optical isotropy and dimensional stability. The resistivity of IZO with 7.5 wt % ZnO film [IZO(7.5)] is 2.9X 10(-4) Omega cm, which is 33% lower than that of tin doped indium oxide film (ITO) and remains unchanged even after annealing at 180 degreesC 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 degreesC. 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. (C) 2004 American Vacuum Society.