Effect of Sputtering Power on the Structure and Optical Properties of Radio Frequency Sputtered-ZnS Thin Film

Abstract

ZnS thin films were deposited on glass substrates by radio frequency (RF) magnetron sputtering. The sputtering power was varied from 60 to 120 W in 20 W increments. The effects of the sputtering powers on the structural and optical properties of the ZnS thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy. XRD showed that the films were polycrystalline with a cubic structure and preferential orientation along (111) the directions. ZnS thin films deposited at higher sputtering power showed better crystallinity than that of the films deposited at lower sputtering power. FESEM images of the surface morphology clearly show that a high sputtering power enhanced the particle size and nucleation of the ZnS thin films. The optical band gap was reduced from 3.96 to 3.47 eV and the optical transmission improved with the sputtering power from 60 to 120 W.