High-quality ZnO films were grown on Si(1 1 1) substrate by MOCVD using a thin AlN buffer layer. A lowtemperature
ZnO buffer layer was further introduced to accommodate the lattice mismatch and thermal expansion coefficient mismatch between the ZnO epitaxial layer and the AlN buffer layer. In situ laser reflectance measurements show that two-dimensional growth has been obtained, and a smooth surface morphology is demonstrated by atomic force microscopy (AFM) measurements. X-ray diffraction (XRD) results show that the ZnO film is a single crystal. The
FWHMs of (0 0 2) and (1 0 2) o-scans for the 2.1 mm thick layer are 410 and 1321 arcsec, respectively. Free excitonic
emission can be observed at low temperature and becomes dominant in the photoluminescence spectra above 120 K.
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