or higher while sharp interfaces in a multilayer structure suitable for optoelectronic devices are obtained at comparatively low growth temperatures. To meet these contradictory requirements a growth scheme has been evolved in which a ZnO buffer layer deposited at about 750 degrees C was found to facilitate high crystalline quality growth of a ZnO over layer even at 400 degrees C. The buffer layer grown at 750 degrees C was found to have its in plane lattice 30 degrees rotated compared to that of the sapphire substrate and so was the case with the ZnO over layer gown at 400 degrees C on the buffer. The full width at half maximum of the high resolution X-ray diffraction rocking curves of (00.2) and (10.4) peaks of ZnO films grown at low temperature on the buffer were found to be similar to 0.18 degrees and -0.28 degrees, respectively, which are comparable to 0.11 degrees and 0.23 degrees as observed in the case of films deposited directly at 750 degrees C and much better than the values of 0.46 degrees and 0.48 degrees seen in case of the films grown at 400 degrees C without any buffer layer. The buffer assisted low temperature ZnO growth also decreased the r.m.s. value of the surface roughness of the film to about 8 angstrom from about 40 angstrom of the one grown at high temperature without any buffer. (c) 2005 Elsevier B.V All rights reserved.