Effect of pH value on the structures and optical properties of chemical bath deposition cadmium sulfide thin films

Hexagonal CdS thin films with a strong (002) orientation were successfully prepared by chemical bath deposition (CBD) using the reaction between CdCl2 and CS(NH2)2. A commonly available CBD system was successfully modified using a wetting agent (polyglycol) without agitation. The influence of pH value on the chemical bath deposition process was studied. It was found that pH value of the solution plays a vital role on the quality of the CdS films. The results of XRD indicated that the increase of hydroxide concentration in the bath results in the second phase of Cd3(OH)5(NO3). The optical transmission of the films is in the 75-95% range for the wavelength region above the band gap absorption, which makes them appropriate as window material in solar cells.