Backscattering analysis of short period ZnO/MgO superlattices

In this work, Rutherford Backscattering and Channeling (RBS/C) studies and Transmission Electron Microscope (TEM) characterization of ZnO/MgO short period superlattices (SLs) grown on crystalline a- and c-plane ZnO substrates are presented. All structures were obtained using Molecular Beam Epitaxy. ZnO and MgO layers were deposited sequentially and their thicknesses were controlled by the growth time. The structures were composed of 30-80 pairs of thin, 1-3 nm, layers of ZnO and MgO. High-resolution TEM was used to control the quality of the SLs. The angular dependence of the backscattering yield was measured across off-normal channels to determine the strain in the structures and lattice constants in relaxed, thick MgZnO layers. Channeling measurement revealed that the growth of ZnO/MgO SLs was nearly perfect, as the chi(min) value in the backscattering yield for the SLs is almost the same as for the ZnO substrate, TEM imaging showed that the growth of the SLs was coherent and the MgO layers retained the wurtzite structure. These results allow to conclude that the in-plane lattice constants of the wurtzite MgO layers in the SLs are like in bulk ZnO. No traces of foreign phase precipitates were found.