Optical Properties of Hexagonal MgxZn1−xO Thin Films Deposited by RF Reactive Magnetron Sputtering

In this work, radio frequency reactive magnetron sputtering was used to grow MgxZn1−xO thin films on glass substrates as a function of substrate temperature. The effect of substrate temperature on crystal structure, elemental composition, and optical characteristics was examined by X-ray diffraction, energy-dispersive X-ray spectroscopy, and UV-Vis transmittance spectroscopy. All MgZnO thin films had a preferential orientation along the (002) plane, signifying robust c-axis growth perpendicular to the substrate and affirming the hexagonal wurtzite structure typical of ZnO. The crystallite size ranged from 7.97 to 12.98 nm, with the maximum value achieved at 250℃. The elements Zn, Mg, and O were identified, and the Mg composition was determined to be x = 0.33 in MgxZn1−xO. Thin films exhibited significant optical transparency, with an average transmittance of around 95% within the visible spectrum. The optical band gap, ascertained by Tauc plots, exhibited a slight increase from 3.80 to 3.86 eV with rising temperature. The refractive index, extracted from the Swanepoel method, varied from 2.15 to 2.58. These results underscore the promise of MgZnO thin films for prospective applications in optoelectronic and UV-transparent devices.