Nonpolar a-plane ZnO growth and nucleation mechanism on (100) (La, Sr)(Al, Ta)O3 substrate

Nonpolar a-plane ZnO epitaxial film with [1 1-2 0] orientation was successfully grown on a (1 0 0) (La-0.3,Sr-0.7)(Al-0.65,Ta-0.35)O-3 (LSAT) substrate by a chemical vapor deposition method. The dependence of surface morphologies and epi-film crystallinity on the growth temperature was studied by a scanning electron microscopy and X-ray diffraction. Room temperature photoluminescence spectra all exhibit a strong near-band-edge emission peak at 378.6 nm without noticeable green band. From high resolution transmission electron microscopy, we found two distinct growth configurations for our a-plane ZnO on (1 0 0) LSAT. To explain the epitaxial properties, we illustrate four possible nucleation sites on (1 0 0) LSAT for two kinds of orientational relationship, i.e. [1 0-1 0](Zno)//[0 1 1](LSAT) and [0 0 0 1](Zno)//[0 1 1](LSAT). (C) 2010 Elsevier B.V. All rights reserved.