High sensitivity and fast response at the room temperature of SnO2:CuO/PSi nanostructures sandwich configuration NH3 gas sensor

Abstract

In this study, SnO2:CuO nanocomposites with different CuO contents and photo electro chemical porous silicon Psi layer have been successfully synthesized to form SnO2:CuO/PSi nanostructure sandwich configuration NH3 gas sensor at the room temperature. Structural aspects of Psi layer and SnO2:CuO nanostructures were inspected by means of X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Sensing performances of the prepared sensor were investigated essentially in a vacuum case and with NH3 gas of different concentrations 50 ppm, 100 ppm, and 150 ppm at the room temperature. XRD analysis showed a small nanocrystallite and a large specific surface area that could improve the gas sensing application, and the FE-SEM features depicted a tree-like structure that made the material adsorb a huge amount of ammonia molecules. Topography of the area displayed a roughness with a small average grain size surface. The sensing performances of Al/SnO2/PSi/Al, and Al/SnO2:CuO/PSi/Al sensors are governed by the CuO content. The best sensing for NH3 gas was obtained at 30% CuO nanoparticles added to 70% SnO2. The Al/SnO2:CuO/PSi/Al sandwich structures sensor has a fast response and recovery times of 8 sec and 10 sec at the room temperature, respectively, and a high sensitivity to NH3 of about 0.9 owing to the higher value of specific surface area of the SnO2:CuO nanocomposites and the resulting barrier height.