Effects of electron irradiation on the structure and morphology of CaF rSi 111/

With the use of X-ray Standing Waves XSW.and Atomic Force Microscopy AFM., we have studied the structure and morphology of CaF2 films thickness range 3–15 A°.grown on Si 111. before and after modification by electron irradiation. The Ca monolayer of the as-grown CaF2 monolayer relaxes towards the Si substrate. The F bilayer embedding the Ca monolayer has bulk spacing. Low Energy 80–100 eV.Electron-Stimulated Desorption ESD. of fluorine reduces mainly the occupation of the top F layer due to generation of surface color centers. The Ca layer is affected only marginally by the electron bombardment. For 15 A° , CaF2 films the color centers nucleate and form Ca clusters embedded in the film. These clusters are removed under ambient conditions pin hole formation.. Inspection of the holes shows that the Ca clusters penetrate the entire CaF2 film. q2000 Elsevier Science B.V. All rights reserved.