Surface and electrophysical properties study of thin TiO2-SnO2 nanocomposite films

Thin nanocomposite films based on pure tin dioxide with a low content of titanium oxide (0, 1, 3, and 5 mol %) were obtained by solid-phase low-temperature pyrolysis. The thickness of the films obtained was up to 200 nm. The particle size of the TiO₂-SnO₂ nanomaterial lies in the range of 7–13 nm. Atomic force microscopy (AFM) showed that the films have a granular structure with a height difference of 11–114 nm. The surface of the film with a Ti concentration of 5 mol.% has a higher roughness compared to other samples. Force microscopy with a Kelvin probe (KPFM) revealed a surface potential, indicating the existence of a strong surface electric field. A small addition of titanium dioxide (1%) to the tin dioxide structure leads to the appearance of peak values of the surface potential, the value of which reaches 1325 mV. Studies of the temperature dependences of the obtained samples showed that the pure SnO₂ film has the maximum resistance values and high nonlinearity. However, with a small addition of titanium dioxide (1%) to tin dioxide, the electrical resistance of the nanosized material sharply decreases and has  indicators 4–5 orders of magnitude lower than those of pure SnO₂ films.