Process optimization for window material CdS thin films grown by a successive ionic layer adsorption and reaction method using response surface methodology

Abstract

Successive ionic layer adsorption and reaction (SILAR) method were used to synthesize of cadmium sulfide (CdS) thin films on support material under different synthesis conditions. Response surface methodology (RSM) based on central composite design (CCD) was used to design the experiment and to optimize selected operating parameters: temperature (°C), dipping time (s) and dipping cycles (cycles). Using RSM, second order polynomial equation was obtained for optical band gap of the films by multiple regression analysis. Analysis of variance revealed that the proposed model was adequate. According to the results of RSM, optimum synthesis conditions of CdS thin films were determined to be temperature of 30.1 °C, dipping time of 29.5 s and dipping cycles of 30 cycles. Band gap of CdS (2.43 eV) in the optimized synthesis condition was in good agreement with the value predicted by the second order polynomial equation (2.36 eV), thereby confirming its validity. The samples were characterized using X-Ray diffraction, scanning electron microscope and ultraviolet–visible spectroscopy measurements.