Investigation of electrophysical, photo- and gas-sensitive properties of ZnO-SnO2 sol-gel films

Thin nanocomposite films based on tin dioxide with a low content of zinc oxide (0.5-5 mol.%) were obtained by the sol-gel method. The synthesized films are 300-600 nm thick and contains pore sizes of 19-29 nm. The resulting ZnO-SnO2 films were comprehensively studied by atomic force and Kelvin probe force microscopy, X-ray diffraction, scanning electron microscopy, and high-resolution X-ray photoelectron spectroscopy spectra. The photoconductivity parameters on exposure to light with a wavelength of 470 nm were also studied. The study of the photosensitivity kinetics of ZnO-SnO2 films showed that the film with the Zn:Sn ratio equal to 0.5:99.5 has the minimum value of the charge carrier generation time constant. Measurements of the activation energy of the conductivity, potential barrier, and surface potential of ZnO-SnO2 films showed that these parameters have maxima at ZnO concentrations of 0.5 mol.% and 1 mol.%. Films with 1 mol.% ZnO exhibit high response values when exposed to 5-50 ppm of nitrogen dioxide at operating temperatures of 200 & LCIRC;C and 250 & LCIRC;C.