Epitaxial growth of ZnO thin films on ScAlMgO4 (0001) by chemical solution deposition

Epitaxial zinc oxide films were produced on the low misfit (0.3%) substrate ScAlMgO4 (000 1) by chemical solution deposition (CSD). Epitaxial growth of ZnO films was achieved by spin coating a precursor solution of zinc acetate dihydrate and ethanolamine in 2-methoxyethanol, heating at 300degreesC, then at 500degreesC, and finally at 850degreesC. X-ray diffraction (theta/2theta-scans/off-axis phi-scans) as well as electron diffraction show that the axes a and c of ZnO and ScAlMgO4 are parallel. The absolute orientation of the ZnO film was determined by electron microdiffraction patterns to be [0 0 0 (1) over bar]. Electron microscopy did not reveal any reaction between film and substrate. The structure of the interface between ZnO and ScAlMgO4 was characterized in detail by high-resolution TEM methods. Exit wave reconstruction from focus series was carried out to localize the positions of atoms at the interface. It was found that the ZnO film coherently continues the terminating tetrahedral (Mg,AI)O-4 layer of the ScAlMgO4 substrate to result in an ABAB stacking of the oxygen layers across the interface as in the wurtzite structure. The structural model is in agreement with the absolute orientation of the ZnO film. (C) 2002 Elsevier Science B.V. All rights reserved.