Chemical and gas sensing property tuning of cadmium sulfide thin films

•The CBD technique was used to synthesize and alter chemical compositions of CdS thin films.•The Cd contents increase with the rise in the CBD deposition period, which affect the composition of CdS thin films and induces defects in the film.•The prolonged deposition time produce a huge CdS micro-balls like morphology.•Such CdS films showed low-temperature gas sensing behavior to NO2 gas with an encouraging outcomes. A simplistic chemical bath deposition (CBD) technique was used to synthesize the hierarchical morphology of cadmium sulfide (CdS) thin films with altered chemical compositions. The novelty of the work does not lies in the surface morphology of the product, but is found in the influence of the CBD reaction time (mainly after post-optimization) on the Cd contents in the films, subsequently the presence of defects and consequently their electrical conductivity and NO2 gas sensing performance. The morphology of the CdS thin films was characterized by field-effect scanning electron microscopy and defects estimated using photoluminescence spectroscopy. The increment in the deposition time affects the precursor contents in the produced film effectively. In the case of the CdS, the Cd contents increase with the rise in the CBD deposition period. Consequently, it affects the presence of the secondary phase and the conductivity of the compound. As the concentration of the films slightly differs from the standard value, we utilized the films for the sensor application. The low-temperature gas sensing measurements of this Cd-rich CdS structure to NO2 gas were carried out, and we found encouraging outcomes.