Microstructural Characterization of Chemical Bath Deposition Synthesized CdS Thin Films: Application as H₂S Sensor

Microstructural characterization of cadmium sulphide (CdS) thin film prepared by chemical bath deposition (CBD) method was studied and there sensing properties for hydrogen sulphide (H ₂ S) is presented. Characterization techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) were utilized to study the microstructure of the films. The films are polycrystalline as revealed from XRD and SEM with average particle size value of ∼12.5 nm measured using Scherrer equation neglecting instrumental and strain broadening. Cubic structure is revealed from XRD and selected area electron diffraction (SAED) pattern. TEM shows CdS nanoparticles in the range 15–20 nm. Porous microstructure with average rms roughness of ∼7.3 nm is revealed from SEM and AFM measurements. The gas sensing characteristics were obtained by measuring the sensitivity as a function of operating temperature. Significantly high sensitivity of ∼54% at a reasonably low temperature of 100 °C was exhibited in presence of 200 ppm H₂S.