Doped-fluorine on electrical and optical properties of tin oxide films grown by ozone-assisted thermal CVD

Transparent conductive fluorine-doped tin oxide (FTO, SnO2: F) films were grown using a low-pressure metallorganic chemical vapor deposition (LP-MOCVD) with tetramethyltin (TMT), oxygen containing 2.96 mol % ozone (O3), and hydrofluoric acid (HF) as a dopant. Using ozone contained oxygen instead of pure oxygen, the substrate temperature could be reduced by ∼100°C while maintaining a growth rate similar to that of tin oxide film. Growth rate of FTO film increased with the flow rate of TMT, however, adherence strength between the film and glass decreased. Resistivity of FTO thin films decreased with the TMT and HF flows over most of ranges investigated, while the resistivity increased rapidly with respect to excessive flow of the TMT over 300 sccm. Optical transmittance of FTO film was about 80% at 550 nm, and the variation as a function of HF flow rate was not significant. FTO film prepared at an optimum condition showed a minimum resistivity of 1.09× 10-3 cm, a mobility of 19 cm2 Vs, and a carrier concentration of 3.05× 1020 cm-3.