Effect of GaN buffer layers on the polarity and properties of ZnO epilayers on nitrided c-Al2O3 by MBE
Abstract
ZnO epilayers were grown on nitrided c-Al2O3 substrates by MBE and the effect of the deposition temperature for GaN buffer layers on the polarity of ZnO epilayer and their properties such as structural and optical properties were investigated. Zn-polar ZnO was normally obtained by using the low temperature GaN buffer layer at 650 °C, while O-polar ZnO were obtained by the high-temperature GaN buffer layer at 850 °C. PL spectra for Zn-polar and O-polar ZnO epilayers, PL spectra were dominated by donor-bound exciton at 3.361 eV and acceptor-bound exciton at 3.356 eV, respectively. It was found that the position of emission peak was affected by the strain in the ZnO layer. PL spectra observed in ZnO epilayers with different polarities are discussed together with their reflectance spectra and strains of ZnO epilayers with different polarities. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
