CVD preparation and characterization of tin dioxide films for electrochemical applications

SnO 2 films have been succesfully prepared by chemical vapour deposition (CVD) by reaction of SnCl 2 with O 2 and a value of the activation energy of 58 kJ mol -1 has been measured. The temperature range 450–500 °C has been found to be the optimum for the reaction with resistivities of the films of 9×10 -4 Ω cm on silicon and 6×10 -4 Ω cm on Pyrex. These two values are the lowest reported so far for SnO 2 films which have not been deliberately doped. For their use as transparent conducting films, a figure of merit of 9.87×10 -3 □ Ω -1 was found for a 0.8 µm thick film; this is also the highest reported so far. Characterization of the films by XRD showed a preferred [200] orientation and the grain size obtained from the XRD and SEM micrographs was in excess of 0.4 µm. The SnO 2 films, when tested in an eletrochemical cell, were unstable. A surface electrochemical process has been suggested for the disintegration.