Thin films Of In2O3(ZnO)(m) (m = 5), having two-dimensional layered structure, were synthesized by RF magnetron sputtering technique on (0001) sapphire substrate. Effects of sputtering atmosphere and post-annealing on crystallinity and mosaic structure of the films were investigated by transmission electron microscopic (TEM) observations and X-ray pole-figure measurements. It was indicated that high oxygen partial pressure is necessary for the formation of layered structure and that the crystallinity was improved by post-annealing oxygen gas. It was also found that electric conductivity was steeply suppressed by annealing. The mechanisms of the suppression of electric conductivity and the formation of layered structures are attributed to ordering of the defects associate with In ions. (C) 2002 Elsevier Science B.V. All rights reserved.