Growth and hydrogenation of epitaxial yttrium switchable mirrors on CaF2

E. S. Kooij*, J. H. Rector, D. G. Nagengast, J. W.J. Kerssemakers, B. Dam, R. Griessen, A. Remhof, H. Zabel

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)


Rutherford backscattering (RBS) ion channeling measurements and X-ray diffraction experiments are performed to study the epitaxial nature of as-deposited yttrium on CaF2〈111〉 substrates and the effect of hydrogenation on the crystalline quality. The RBS and X-ray results clearly demonstrate the unique epitaxial relation between as-deposited films and the substrate, which is preserved upon loading with hydrogen. X-Ray diffraction reveals: (i) a remarkably large lattice expansion in the direction normal to the substrate, which decreases with increasing film thickness; and (ii) an in-plane compression of the lattice. This peculiar result is related to the difference in thermal expansion coefficients of film and substrate. RBS ion channeling measurements reveal a thickness dependence of the mismatch-induced stresses. As expected, the stresses relax with increasing distance from the film/substrate interface, but surprisingly, even with films as thick as 400 nm considerable dechanneling is still observed at the film surface. Film quality, i.e. the film/substrate mismatch as well as the induced stresses and their relaxation, are discussed in relation to atomic force microscopy (AFM) results on these epitaxial films.

Original languageEnglish
Pages (from-to)131-142
Number of pages12
JournalThin Solid Films
Issue number1-2
Publication statusPublished - 1 Jan 2002

Bibliographical note

Funding Information:
We thank N.J. Koeman for preparation of samples and technical support. Fruitful discussions with A.T.M. van Gogh and S.J. van der Molen are gratefully acknowledged. This work is part of the research program of the Stichting voor Fundamenteel Onderzoek der Materie (FOM), financially supported by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) and Philips Research. Additionally, the work is supported by the TMR Research Network ‘Switchable metal-hydride films’ and by the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie under contract 03-ZA4BC1-0. The use of the RBS facility at the AMOLF-FOM institute in Amsterdam is gratefully acknowledged.


  • Epitaxy
  • Molecular beam epitaxy (MBE)
  • Rutherford backscattering spectroscopy (RBS)
  • Switchable mirrors
  • X-Ray diffraction (XRD)
  • Yttrium


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