1. Introduction P. Chelvanathan 1, Y. Yusoff 2, M. I. Hossain 1, M. Akhtaruzzaman 1, M. M. Alam 3, Z. A. AlOthman 3, K. Sopian 1, N. Amin 1,2,3 1 Solar Energy Research Institute, The National University of Malaysia, 43600 Bangi, Selangor, Malaysia 2 Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, The National University of Malaysia, 43600 Bangi, Selangor, Malaysia 3 Advanced Materials Research Chair, Chemistry Department, College of Sciences, King Saud University, Riyadh 11451, Saudi Arabia * E-Mail: nowshad@eng.ukm.my Structural and Optical Property Evolution of RF-Sputtered ZnS Thin Film In this study the structural and optical properties evolution of ZnS thin films have been investigated. ZnS thin films were fabricated by RF sputtering method with RF power and operating pressure varied from 50 – 110 W and 7 – 17 mTorr respectively. The deposited ZnS films then were characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometer (XRD), Atomic Force Microscopy (AFM) and Hall measurement equipment to elucidate the structural and optical.  It can be clearly observed that for higher operating pressure of 17 mTorr and 13 mTorr which correspond to sample B-ZnS and D1, the nature of the crystal structures are amorphous as the XRD readings did not indicate any clear distinct peak(s). However, as the working pressure is decreased below 10 mTorr as for sample D2 and D3, a distinct peak is observed which is centred at 28. 64 º which correspond to cubic phase crystals with (111) plane The cubic phase of (111) plane has an increasing peak centred at 28.5º as the RF in increased from 70 W to 110 W. At the same time, cubic phase of (220) plane is formed for film deposited at 110 W, but the relatively insignificant when compared to the (111) plane which is the dominant. Major Findings and Discussions Conclusion : Optimum Deposition Parameter of ZnS Experimental & Characterization Procedures Surface morphology probed by Scanning Electron Microscope XRD patterns with various annealing temperature Substrate Cleaning Process Methanol, acetone, methanol, DI water sonification for 15 minutes in each solvent Substrate Cleaning Process Methanol, acetone, methanol, DI water sonification for 15 minutes in each solvent RF-Sputtered ZnS Film Base pressure = 10 -4 Torr Argon Flow = 7-17 SCCM DC Power = 50-110 W Sub. Rotation = 10 RPM Sub. Temperature = RT Deposition Time = 80 min. Mo Thickness = 500 nm RF-Sputtered ZnS Film Base pressure = 10 -4 Torr Argon Flow = 7-17 SCCM DC Power = 50-110 W Sub. Rotation = 10 RPM Sub. Temperature = RT Deposition Time = 80 min. Mo Thickness = 500 nm Characterization Methods XRD FESEM UV-ViS AFM Characterization Methods XRD FESEM UV-ViS AFM Band gap (a) Operating time variation (b) RF power variation RMS Surface Roughness (a) Operating time variation (b) RF power variation (a) (b) (a) (b) Sample ParameterParamet er Value(s) B-ZnS Baseline17mTorr 50 W D1 Operating Pressure 13 mTorr D29 mTorr D37 mTorr E1 RF Power 70 W E290 W E3110 W B-ZnSD2 E3 ParametersValue Operating pressure7 mTorr RF power110 W Substrate temperature200 ºC ENGE 2014, 16 th to 19 th Nov 2014, Jeju, Korea