Analysis of sulphur deficiency defect prevalent in SILAR-CdS films

When cadmium sulphide (CdS) films are deposited using successive ionic layer adsorption and reaction (SILAR) process, a sulphur deficiency defect is always observed. The reason for this defect is addressed in the present work, by systematically analyzing the increasing pattern of Cd²⁺ions available in the anionic solution bath during the SILAR dipping cycles. The variation of the Cd²⁺ ion concentration in the anionic solution bath with respect to the number of cycles is analyzed in detail using inductive coupled plasma (ICP) analysis. Moreover, the corresponding sulphur deficiency generated in the CdS thin films is also analyzed using the energy dispersive X-ray analysis profiles, appropriately correlated with the ICP results. The optical transmittance and the thickness measurements are carried out as supplementary studies to support the analysis on the sulphur deficiency. The obtained results may be useful for rectifying this sulfur deficiency defect which is commonly occurred in CdS films deposited using chemical bath deposition as well as SILAR methods.