Self-patterned nanocrystals (NCs) with size, shape and composition fluctuation similar to quantum dots (QDs) in conventional semiconductors were formed in epitaxial Zn0.3In1.4Sn0.3O3-delta (ZITO) thin films on (I 1 1) yttria-stabilized zirconia (YSZ) substrate. The diameters of the NCs range from 5 to 30 nm. Chemical composition in and around NCs was analyzed by high-angle-angular-dark-field (HAADF) imaging and nanobeam composition line scanning in an advanced (scanning) transmission electron microscope. The NCs are rich in heavier elements compared with their surrounding medium. The formation of self-patterned NCs and its tuning effects on charge transport and optical transparency of ZITO films are also discussed. (C) 2007 Elsevier B.V. All rights reserved.