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

Abstract

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[Formula: see text]C and 250[Formula: see text]C.