Synthesis and characterization of Bi doped ZnO thin films using SILAR method for ethanol sensor

•Morphological -structural changes induced by addition of Bi in ZnO structure.•Bi doped ZnO reduced the bandgap value of 3.17 eV.•Morphological studies confirmed the grain growth at 3% of Bi doped ZnO films.•Sensitivity improved from 50 to 60%. Pure and Bi doped ZnO thin films prepared by Successive Ionic Layer Adsorption and Reaction (SILAR) method. The structural analysis shows that prepared films are polycrystalline in nature with preferential orientation along (100), (002) and (101) planes. Scanning electron microscope shows the morphological changes of the films with respect to increase in doping concentration. The average optical absorption value of all films was in the near visible range and the band gap of the films varies from 3.21 to 3.17 eV. The gas sensing study shows a maximum response of the films at 1000 ppm of ethanol was found to be around 60% with an operating temperature of 400 °C.