Influence of Mg doping on the properties of ZnO films prepared on c-cut sapphire by sputtering

Abstract

Nanostructured ZnO and Mg doped ZnO (Mg:ZnO) thin films were prepared on c-cut sapphire substrate at 700°C by rf sputtering. The influence of Mg doping on the structural, luminescence, optical and morphological properties were investigated systematically. XRD pattern of both the films show highly c-axis oriented wurtzite hexagonal structure. A slight shift in the (002) peak position establish the effective doping of Mg into ZnO lattice. The blue shift in the PL emission for Mg:ZnO film indicates the modulation of band gap caused by Mg addition, which is also confirmed by the increase in energy gap value from 3.34 and 3.45eV. The significant change in surface morphology of the films from nanowires into nanoring, formed by a novel self assembly process, highlights the importance of Mg doping (20at.%) into ZnO.