The structural, electrical and optical properties of CdS thin films as a function of pH

Cadmium sulfide (CdS) thin films have been deposited on glass substrates at 30 °C for 36 h using chemical bath deposition technique. The deposition was carried out in the pH range of 10–12 using aqueous solution of cadmium nitrate and thioacetamide salts. Structure of these films was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Elemental analyses of the films were studied by energy dispersive X-ray analysis (EDX). The optical and electrical properties of the prepared films were analyzed by absorbance spectra and Hall effects measurements, respectively. Influence of the pH on the structural, optical and electrical properties of CdS films was investigated. After all investigations, it was concluded that the pH value of 10 is suitable for producing CdS films by chemical bath deposition technique and the examined properties (good crystallinity and low resistivity) of this film show its feasibility for technological purposes, especially for solar cells.

► CdS thin films were deposited at 30 °C for 36 h by chemical bath deposition.
► It is the first time, isopropylxanthate ligant was used for obtaining CdS films.
► The pH of the chemical bath varied in the range 10–12.
► Resistivity increased from 4.375 × 105 to 8.931 × 105 Ω cm with increase in pH value.
► Band gap of CdS thin films decreased from 2.45 eV to 2.28 eV with increasing pH.