Facile synthesis of Mn doped ZnO for the sensing of ammonia

Abstract

The variation of possessions of Mn doped in ZnO thin films grown by SILAR technique for various Mn concentrations presented. Thin films of Mn doped ZnP were deposited and uniformly annealed at 300 °C for a 30 min. The annealed films are then characterized by various methods like XRD, SEM, EDAX, VSM respectively. The x-ray diffraction studies confirm the emergence of ZnO. From the SEM, various morphologies were identified based on concentration of the solution bath employed. Due to this reason, spherical shoot, rice and flower morphologies were observed on the surface of the films. These morphologies may influence the application of ammonia gas sensor. From compositional analysis (EDAX), the presence of dopant and the variation in composition of doped materials were estimated. Magnetic studies shows, these films show ferromagnetic behaviour at room temperature. The ammonia gas response of the Mn doped ZnO thin films varied with Mn concentration of 0, 5 and 10. The outcomes of the gas sensing experiments showed that the Mn doped ZnO thin film was more sensitive to ammonia, but that sensitivity decreased as gas pressure increased. Ammonia gas showed an increase in the acidic surface properties of Mn-doped ZnO thin film. At room temperature, Mn-doped ZnO (0 %, 5 % and 10 %) showed responses of 19.20, 27.61 and 32.26 to 100 ppm NH3 gas, which were significantly higher than those of ZnO. The Mn-doped ZnO sensor shows excellent selectivity compared to ZnO and has good stability.