Characteristics of Fluorine-doped tin oxide thin films grown by Streaming process for Electrodeless Electrochemical Deposition

This work investigated the characteristics of SnO$_{2}$: F films grown by Streaming Process for Electrodeless Electrochemical Deposition (SPEED). Stannic chloride (SnCl$_{4})$ and ammonium fluoride (NH$_{4}$F) was dissolved in a mixture of deionized water and organic solvents. The preheated substrate temperature was varied between 450 and 530$^{\circ}$ C. High quality SnO$_{2}$: F films were grown at all the substrate temperatures studied. The typical film thickness was 250 nm. XRD shows that the grown films are polycrystalline SnO2 with a tetragonal crystal structure. The average optical transmission of the films was around 93{\%} throughout the wavelength of 400 to 1000 nm. The lowest electrical resistivity achieved was 6 x 10$^{-4} \Omega$ cm. The Hall measurements showed that the film is an n-type semiconductor, with the highest carrier mobility of 8.3 cm$^{2}$/V.s, and concentration of 1 x 10$^{21}$ cm$^{-3}$. The direct band gap was determined to be 4 eV from the transmittance spectrum.