  Unlike other II-VI semiconductors, CdO-based transparent oxide has great
potential application for the fabrication of many optoelectronic devices. In
this work, we study the growth of CdxMg1-xO alloys on m- and on c-plane
sapphire substrates in Cd-rich to Mg-rich conditions using the plasma-assisted
molecular beam epitaxy method. A structural and morphological study of CdMgO
random alloys was carried out using X-ray diffraction and Atomic Force
Microscope (AFM) techniques whereas composition analysis was done by
Energy-dispersive X-ray (EDX) spectroscopy method. The optical properties of
thin films were investigated by UV-Vis spectroscopy at room temperature. X-ray
analysis confirmed the presence of cubic rock salt structure with <111> CdMgO
crystallographic orientation on c-plane sapphire and <110> CdMgO preferential
orientation on m-plane sapphire. The surface roughness was measured by the AFM.
From the absorption curve, the optical bandgaps were determined using Tauc
relation and it was found that the bandgap of films is influenced by the
incorporation of Mg2+ ions into the CdO lattice. Bowing parameter was
calculated both for samples on m- and c- sapphires.
