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The high thermal conductivity, high electron mobility, the direct wide band gap, and large exciton binding energy of zinc oxide (ZnO) make it appropriate for a wide range of device applications like light-emitting diodes, photodetectors, laser diodes, transparent thin-film transistors, and so forth. Among the semiconductor metal oxides, zinc oxide (ZnO) is one of the most commonly used gas-sensing materials. The gas sensor made of nanocomposite ZnO and Ga-doped ZnO (ZnO:Ga) thin films was developed by the sol–gel spin coating method. The gas sensitivity of gallium-doped ZnO thin films annealed at 400, 700, and 900 °C was studied for ethanol and acetone gases. The variation of electrical resistance of gallium-doped ZnO thin films with exposure of ethanol and acetone vapors at different concentrations was estimated. Ga:ZnO thin films annealed at 700 °C show the highest sensitivity and shortest response and recovery time for both ethanol and acetone gases. This study reveals that the 5 at. % Ga-doped ZnO thin film annealed at 700 °C has the best sensing property in comparison to the film annealed at 400 and 900 °C. The sensing response of ZnO:Ga thin films was found higher for ethanol gas in comparison to acetone gas.

Swift heavy ion (SHI)-induced modification in structural and optical properties of ZnO thin films deposited by sol-gel method is investigated. These thin films were irradiated by 120 MeV ions of Ag ?9 at various ion fluencies. The structural properties were studied using grazing incidence X-ray diffraction, and it shows that the average crystallite size of ZnO films is observed to decrease by the irradiation. The band gap of ZnO films is varied little without any appreciable change in the shape of near-band-edge absorption by SHI irradiation. It is also observed that the average transmittance in the visible region is reduced from *88 to *45 %. It can also be mentioned that the interference fringes from the transmittance spectra disappear on exposure to irradiation. The modifications of the observed structural and optical properties are explained in terms of defects induced by energy deposited in the lattice by SHI irradiation.