Influence of Ba doping concentration on the physical properties and gas sensing performance of ZnO nanocrystalline films: Automated nebulizer spray pyrolysis (ANSP) method

Automated nebulizer sprayed Ba doped zinc oxide films were investigated. X-ray diffraction study reveals the polycrystalline hexagonal crystal structure with higher preferential orientation of (002). Compositional analysis of EDAX confirms the essential element of Ba, Zn and O. The FESEM shows the changes of spherical shape structure to flake net-like shape and sprout like spherical structure with average grain size is ∼100 nm due to the Ba concentration. The coated films are highly transparent in the visible region with a transmittance higher than 74%, and have an optical band gap energy values are increased from 3.22 eV to 4.02 eV depending on the Ba doping concentration. Interparticle like grains, grain boundary effect of deposited films is studied by complex impedance spectroscopy. The gas sensing response of BaxZn1-xO films shows NH3 > C2H6O > C3H6O with the function of temperature (50 °C to 350 °C) and gas concentration (100 ppm to 900 ppm).