Effects of lattice-matched substrates on growth of ZnO epitaxial films were studied. ZnO thin films were grown on single-crystalline InGaO3(ZnO)(6) (IGZO) layers, which have small lattice mismatches of similar to 0.8% and similar to 2.2% in a- and c-axes, respectively. Epitaxial ZnO films were grown with the epitaxial relationship between the ZnO film and the single-crystalline IGZO of [0001](ZnO)//[111](IGZO)//[111](YSZ) and [1120](ZnO)//[1201](IGZO)//[110](YSZ). The use of the lattice-matched substrate and optimization of film microstructure and post-annealing condition led to atomically flat surfaces at maximum process temperatures as low as 700 degrees C. A large Hall electron mobility -80 cm(2) (V s)(-1) (N-e: similar to 2.8 X 10(18) cm(-3)) was obtained even if the film thickness was only 150 nm although comparable mobilities have been reported on films having much larger thicknesses (similar to 1000 nm) fabricated at higher temperatures similar to 1000 degrees C. (c) 2004 Published by Elsevier B.V.