Photoluminescence studies of (Mg, Zn)O epilayers via metalorganic vapor phase epitaxy on m-plane ZnO substrates

Hexagonal wurtzite MgxZn(1-x)O intrinsic and gallium-doped epilayers were deposited on m-plane ZnO substrates by metalorganic vapor phase epitaxy. We demonstrate a linear dependence in the energy gap with increasing Mg concentration for n-type alloys 0.10 <= x <= 0.30 and for intrinsic alloys 0.20 <= x <= 0.50. We show a comparison of m-plane and c-plane MgxZn1-xO indicating a dependence of the electronic activity of Mg with crystallographic orientation. Further, we demonstrate an increase in exciton localization associated with the strong enhancement of photoluminescence intensity and reduction in the near band-edge full-width at half-maximum with increasing Mg concentration. Additionally, the thermal activation energy corresponding to the localization is considered. (C) 2011 American Institute of Physics. [doi:10.1063/1.3569746]