Homoepitaxial growth and characterization of ZnO(0001) thin films grown by metalorganic chemical vapor epitaxy

We study the properties of Zn-face ZnO(00.1) layers grown on the Zn-face of high quality ZnO(00.1) single crystal wafers by metalorganic chemical vapour epitaxy. The layers are grown directly on the ZnO substrates without any treatment of the substrate before starting the growth. The growth temperature is varied between 600-1050 degrees C while the reactor pressure is kept at 50 Torr. Atomic force microscopy reveals monolayer steps with a step length of 170 nm. The root-mean-square roughness is 0.1 nm over a 20x20 mu m(2) area. A two-dimensional step morphology is only seen for growth temperatures above 950 degrees C. Layers grown below 950 degrees C exhibit very rough three dimensional surface morphologies. The full width at half maximum for x-ray rocking curves is 22 arcsec and 36 arcsec across the (00.2) and the (20.1) reflections, respectively. This is comparable to the rocking curve widths of the as-received substrates. The peaks of the ZnO epitaxial thin film and the substrate are indistinguishable in reciprocal space maps. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim