Morphology, composition and electrical properties of SnO₂:Cl thin films grown by atomic layer deposition

Chlorine doped SnO₂ thin films were prepared using atomic layer deposition at temperatures between 300 and 450 °C using SnCl₄ and H₂O as the reactants. Composition, structure, surface morphology, and electrical properties of the as-deposited films were examined. Results showed that the as-deposited SnO₂ films all exhibited rutile structure with [O]/[Sn] ratios between 1.35 and 1.40. The electrical conductivity was found independent on [O]/[Sn] ratio but dependent on chlorine doping concentration, grain size, and surface morphology. The 300 °C-deposited film performed a higher electrical conductivity of 315 S/cm due to its higher chlorine doping level, larger grain size, and smoother film surface. The existence of Sn²⁺ oxidation state was demonstrated to minimize the effects of chlorine on raising the electrical conductivity of films.