Layer-by-layer growth of high-optical-quality ZnO film on atomically smooth and lattice relaxed ZnO buffer layer

The growth mode of ZnO thin films can be well regulated in a molecular layer-by-layer growth by employing a ZnO buffer layer deposited on a lattice-matched ScAlMgO4 substrate and annealed at high temperature. The annealed buffer layer has atomically flat surface and relaxed (strain-free) crystal structure. The intensity oscillation of reflection high-energy electron diffraction persisted for more than a 100-nm film deposition under optimized conditions on such a buffer layer. Thus prepared thin films show free exciton emissions in a 5 K photoluminescence spectrum and excited-state exciton resonance structures in a reflection spectrum, both indicating very high optical quality. (C) 2003 American Institute of Physics.