Highly selective and sensitive CdS thin film sensors for detection of NO2 gas

Abstract

We demonstrate the preparation of cadmium sulfide (CdS) thin films via a facile chemical bath deposition method. The CdS films have been characterized by various techniques, such as, X-ray diffraction (XRD), energy dispersive X-ray (EDAX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Gas sensing performance of CdS thin films was tested at room temperature (38 °C) for oxidizing (NO₂, Cl₂) and reducing gases (H₂S, NH₃, C₂H₅OH, CH₃OH). CdS films were found to be highly selective and sensitive to NO₂ with a maximum response of 61% at 200 ppm with a fast response time of 50 s and 81% stability. Furthermore, the sensor is able to detect up to low (5 ppm) concentration of NO₂ gas with a reasonable response (5%). The plausible mechanism(s) of NO₂ sensing has been discussed.