A Study of Stacked Buffer Layers for the Epitaxial Growth of Zn0.58Mg0.42O Films on c-Sapphire by Pulsed Laser Deposition

We report the growth of hexagonal Zn0.58Mg0.42O thin films on a c-plane sapphire substrate via pulsed laser deposition using Zn0.7Mg0.3O/Zn0.9Mg0.1O/ZnO stacked buffer layers of various thicknesses. The effects of the stacked buffer layer thickness on the structural and optical properties were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), energy dispersive X-ray (EDX), and UV–visible spectroscopy. The XRD results showed that whereas the cubic and hexagonal phases formed without a stacked buffer layer, only the hexagonal Zn0.58Mg0.42O phase grew in the stacked buffer layer configuration. The stacked buffer layer could accommodate structural inconsistencies and prevent phase separation in high-Mg films. As the thickness of each stacked buffer layer decreased, the crystalline quality of the hexagonal Zn0.5Mg0.5O film was enhanced.