A CuScO2(0001) epitaxial film with a thickness of a few hundred nanometers; was successfully grown on an a-plane sapphire substrate by combining the two-step deposition and post-annealing techniques. The film was single-phase with a rhombohedral crystal structure and showed six-fold rotational symmetry in the basal plane, indicating that the film had a twinned domain structure. The orientation relationships of the film with respect to the substrate were CuScO2[3R](0001)//sapphire(11 (2) over bar0) and CuScO2[3R][11 (2) over bar0]//sapphire[0001]. The average optical transmittance of the film was higher than 60% in the visible/near-infrared regions, and the energy gap for direct allowed transition was estimated to be 3.7 eV. The p-type conduction of the film was confirmed by Hall measurement. The electrical conductivity, carrier concentration, Hall mobility, and Seebeck coefficient of the film at room temperature were 1.0 x 10 (3) S cm(-1), 4.5 x 10(16) cm(-3), 1.4 x 10(-1) cm(2)V(-1) s(-1), and +968 mu V K-1, respectively. The activation energy estimated from the temperature dependence of the carrier concentration was 0.62 eV. (C) 2008 Elsevier B.V. All rights reserved.