An inhibitory effect on CdS thin films produced by the electrodeposition method

Abstract This study investigates the effect of a decreased reaction rate, achieved using an inhibitor, on CdS thin films produced by the electrodeposition method. CdS thin films were electrodeposited onto an indium-tin oxide (ITO)-coated glass substrate using a three-electrode system. Cadmium chloride (CdCl₂) is used as a cadmium (Cd) precursor, and sodium thiosulfate (Na₂S₂O₃) is used as a sodium precursor, while sodium sulfite (Na₂SO₃) was used for the first time as an inhibitor to reduce the reaction rate. Structural, optical, and morphological analyses of CdS films were performed using X-ray diffraction, UV-vis spectroscopy, SEM, and EDX, respectively. XRD analysis showed that in the absence of inhibitor use, hexagonal Cd peaks formed in addition to cubic CdS peaks. It was observed that the Cd peaks completely disappeared with a decrease in reaction rate. The absorption measurements indicated that the calculated energy band values range from 2.1 eV to 2.36 eV. SEM images showed that as the reaction rate slowed, voids and pinholes on the film surfaces completely disappeared. Surface roughness values obtained using SEM images were found to have decreased from 18.8 nm to 10.7 nm. Furthermore, it was observed that the surface resistance values of the films decreased from 0.6079 kΩ cm to 0.0736 kΩ cm depending on the use of Na₂SO₃.