Structural analysis of CdO layers grown on r-plane sapphire (0112) by metalorganic vapor-phase epitaxy

High-quality fully relaxed CdO layers have been grown directly on r-plane sapphire by metalorganic vapor-phase epitaxy. The crystalline structure has been analyzed by high-resolution X-ray diffraction. The structural quality of the (001) oriented layers degrades as the growth temperature decreases, process which is accompanied by the appearance of pyramidal grains as revealed by scanning force microscopy. The lattice parameters, perpendicular and parallel to the sample surface, have been determined by means of reciprocal space maps taken on asymmetrical reflections and measurements of symmetrical reflections at different azimuths. The epitaxial relationships between the CdO layer and the sapphire substrate have been deduced from the recorded pole figures. The quality of these CdO layers paves the way for a new development on the heteroepitaxial growth of other II-VI oxides on sapphire in addition to ZnO. (C) 2004 Elsevier B.V. All rights reserved.