Preparation and properties of sprayed undoped and fluorine doped tin oxidefilms

Thin films of undoped and fluorine doped tin oxide have been prepared on bo rosilicate glass plates by a spray pyrolysis technique. The effect of proce ss parameters, such as tin chloride concentration in the precursor solution , substrate to nozzle distance, carrier gas (air) how rate, substrate tempe rature, and doping level of fluorine in the spray solution, on the physical properties of the tin oxide thin films have been investigated. The grown f ilms were polycrystalline in nature above 350 degrees C, the [110] reflecti on having the maximum intensity in all cases. Films of about 10(-3) Ohm cm resistivity and high visible transparency of about 88% have been obtained a t the optimum substrate temperature of 425 degrees C and fluorine doping co ncentration of 57 at.%. The optical investigations show that the optimized films have a direct allowed bandgap of 4.25 eV and indirect allowed bandgap of 2.71 eV. (C) 1999 Elsevier Science S.A. All rights reserved.