Preparation and characterization of sprayed FTO thin films

Fluorine doped tin oxide (FTO) thin films have been prepared by spray pyrolysis technique with no further annealing. Films with 2.5% of fluorine grown at 400 degrees C present a single phase and exhibit a tetragonal structure with lattice parameters a = 4.687 angstrom and c = 3.160 angstrom. Scanning electron micrographs showed homogeneous surfaces with average grain size around 190 nm. The films are transparent in the visible zone and exhibit a high reflectance in the near infrared region. The best electrical resistivity was 6.3 x 10(-4) Omega cm for FTO with 2.5% of fluorine. The ratio of transmittance in the visible to the sheet resistance are in the 0.57 x 10(-2)-1.96 x 10(-2) Omega(-1) range.