Atomic layer deposition process with TiF_4 as a precursor for depositing metal fluoride thin films

A novel atomic layer deposition process for the preparation of fluoride thin films in a temperature range of 225 °C-400 °C is introduced. The crystallinity, morphology, composition, thicknesses, refractive indices, and transmittance of the films are analyzed. Low impurity levels are obtained at 350 °C-400 °C with good stoichiometry. Refractive indices of 1.34-1.42 for MgF2, 1.43 for CaF2, and 1.57-1.61 for LaF3 films are obtained.