A selective NH3 gas sensor based on (Ag2O)1-x(SnO2)x nanocomposites thin films at various operating temperatures

Abstract

The pulsed laser deposition (PLD) technique was used to prepare the (Ag2O)1-x(SnO2)x nanocomposite thin films with different ratios of x=0, 0.2 and 0.4wt and deposited on glass substrates. The films were subsequently annealed in the air for two hours at 300 °C. The (Ag2O)1-x(SnO2)x nanocomposite was confirmed to have formed by the x-ray diffraction (XRD) investigation. According to field emission scanning electron microscopy (FESEM), the created (Ag2O)1-x(SnO2)x particles were spherical in shape. Energy Dispersive X-Ray Analysis (EDX) is used to confirm the elements in composite films. Atomic Force Microscopy (AFM) analysis shows that the produced films had grains size between 37.68 - 49.57nm and root mean square (RMS) roughness of 4.92-8.22nm. The prepared films have a direct energy gap between 2.06 and 3.36 eV, according to UV-visible (UV-Vis) spectrometer data. The films have been tested for NH3 sensing under various operating temperatures. The observed variations in the gas sensing response's thin film resistance are suggestive of either n-type or p-type conductivity. When reducing gas is present, the resistance of (Ag2O)1-x(SnO2)x films increases when x=0, 0.2wt , indicating that the films are p-type, however, the thin film exhibits the reverse behavior at x=0.4wt, indicating that it is n-type. Additionally, all films produced showed a significant sensitivity to NH3 gas at 95 ppm concentration. The Ag2O thin film had a sensitivity of 50.5% at an operating temperature of 200°C with response and recovery times of 22.5 and 39.6 seconds, respectively. Furthermore, composite thin films showed greater sensitivity than pure silver oxide thin films.

Keywords

• Ag2O- SnO2, Nanocomposites, NH3 gas sensor, Operating temperatures, Pulsed laser deposition.