NaF films: Growth properties and electron beam induced defects

Polycrystalline NaF films were grown by e-beam assisted physical evaporation on amorphous silica substrates kept, during film growth, at constant temperatures ranging from 40°C to 400°C. The structural characterization of the films was performed by X-ray diffraction and by scanning electron microscopy.Irradiating the films with a 15 keV electron beam induced the formation of F and F-aggregate colour centres stable at room temperature. Absorption and photoemission measurements were performed and indicated a dependence of coloration on the deposition conditions.