Effect of concentration of SnCl4 on sprayed fluorine doped tin oxide thin films

Transparent conducting thin films of F:SnO2 have been deposited onto preheated glass substrates by a spray pyrolysis technique by varying the concentration of SnCl4. A fine spray of the source solution using air as a carrier gas has grown films of thickness up to 1108 nm. Optical absorption, X-ray diffraction, Van der Pauw technique for measurement of a sheet resistance and Hall effect measurements at room temperature for determination of carrier density and conductivity has been used. The as deposited films are of polycrystalline SnO2 with a tetragonal crystal structure having preferentially orientation along the (2 0 0) direction with texture coefficient as high as 6.92 with average grain size of 48 nm. The maximum value of figure of merit (61.8 × 10−3 Ω−1) with 87% transmittance at 550 nm has been obtained. The surface morphology of the films has been studied with SEM and AFM techniques. SEM shows continuous periodic arrangement of the smaller grains in between two bigger grains, with pinhole free surface. The films are heavily doped, degenerate and exhibit n-type electrical conductivity. For the optimized sample the values of lowest sheet resistance (Rs) resistivity (ρ) and mobility (μ) are 3.71 Ω, 3.7 × 10−4 Ω cm and 5.81 cm2 V−1 s−1, respectively.