Synthesis and characterization of In doped ZnO thin films for LPG sensing

Thin films of indium doped zinc oxide (In:ZnO) have been deposited onto glass substrates using a facile and inexpensive Spray Pyrolysis method. To reveal the effect of indium concentration on the gas sensing characteristics, thin films were synthesized using different concentration of indium in the precursor. X-ray diffraction (XRD) study indicates formation of crystalline phase of zinc oxide under the prevailing experimental conditions. The scanning electron microscope (SEM) images reveal uniform deposition on the entire substrate surface characterized by granular morphology. A careful observation of the SEM images reveals that nanocrystalline nature of the films, with average grain size ∼ 300 nm. The elemental composition obtained from the Energy Dispersive X-ray Analysis (EDAX) confirms presence of indium along with zinc and oxygen in the synthesized thin films. The gas sensing characteristics of the In-ZnO2 films were investigated for Liquefied Petroleum Gas (LPG) vapours at different operating temperatures in the range of 200 to 320 °C and various vapour concentration values. Interestingly, the In-ZnO thin films exhibited good sensor response in the operating temperature range. The response and recovery times are also in the range of few tens of second. The present results indicate that spray synthesized In-ZnO films have potential towards detection of LPG vapours