Summary: | In this paper, Zn<i><sub>1-x</sub></i>Mg<i><sub>x</sub></i>S thin films were co-sputtered on glass substrates using ZnS and MgS binary target materials under various applied RF power. The compositional ratio of Zn<i><sub>1-x</sub></i>Mg<i><sub>x</sub></i>S films was varied by changing the RF power at an elevated temperature of 200 °C. The structural and optical properties were studied in detail. The structural analysis shows that the co-sputtered Zn<i><sub>1-x</sub></i>Mg<i><sub>x</sub></i>S thin films have a cubic phase with preferred orientation along the (111) plane. The lattice constant and ionicity suggest the presence of a zincblende structure in Zn<i><sub>1-x</sub></i>Mg<i><sub>x</sub></i>S thin films. Zn<i><sub>1-x</sub></i>Mg<i><sub>x</sub></i>S thin films have transmittance over 76%. The extrapolation of optical characteristics indicates that direct bandgaps, ranging from 4.39 to 3.25 eV, have been achieved for the grown Zn<i><sub>1-x</sub></i>Mg<i><sub>x</sub></i>S films, which are desirable for buffer or window layers of thin film photovoltaics.
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