Highly sensitive nitrogen dioxide gas sensors based on sprayed β-In2S3 film

Abstract

Metal sulfides have been studied for their high performances as new sensitive materials for gas detection. CdS has been used recently in view of its high degree of selectivity and sensitivity to NO2. The objective of this work is to replace Cadmium with Indium, which can be a good alternative in order to avoid the toxicity of cadmium. Thus, this work reports the sensing performances of In2S3 material for nitrogen dioxide detection. In2S3 thin films were deposited by spray pyrolysis, which is a simple technology for large area coatings, and with which it is easy to dope the material by the addition of a doping element to the spray solution. Structural, morphological and chemical analyses of the layers obtained were performed by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) methods. Nitrogen dioxide gas was tested using DC electrical characterization. The optimal working temperature was found to be around 200 °C. The response of the material increases from 4 to 64 times by varying the nitrogen dioxide concentration from 200 ppb to 5 ppm at 200 °C. The response time and the effects of humidity and ultraviolet irradiation were also examined. This study demonstrates the possibility of producing sensitive NO2 gas sensors at a low cost based on In2S3 nanoparticles via a spray pyrolysis technology.