Determination of the optimal conditions for the deposition of Cadmium sulfide thin films by chemical bath deposition using Taguchi method

Thin films of Cadmium sulfide (CdS) is one of the promising semiconductor materials which can be used as a tampon materials deposited by chemical bath deposition (CBD) in thin film solar cells thanks to its tunable direct band gap energy, large transmission coefficient and cost effective. The role of the CdS layer is still debated within the scientific community, but the material efficiency obtained with this fine n-type semiconductor layer is very high. It could protect the damage associated with the following spray deposits of defects in the surface of the absorber or adapt the width of the energy band gap between the absorber (~1.2 (eV)) and the window layer (~3.3 (eV)). The aim of this present study is to investigate the influence of deposition parameters of CdS thin films using the L₉ orthogonal array of the Taguchi's design of experiments (DOE) elaborated by CBD method on ordinary glass substrate. The Taguchi design was used to evaluate the effects of four deposition parameters called factors namely the ratios [Cd]/[S], time of deposition, Ammonia concentration [NH4Cl] and volume ratio V(H2O)/V(NH3) on optical properties of elaborated films. The identification of the most influent factor of the deposition process on the band gap energy of elaborated films is also done by employing the analysis of variance (ANOVA). The Taguchi analysis employed in the present investigation led to optimize process parameters for the most optimal deposition conditions. Under the optimized configuration, the CdS films showed optimal gap energy of 2.42 (eV) [1]. The Taguchi analysis employed in the present investigation led to optimize process parameters for the most optimal deposition conditions.