Ellipsometric study of dielectric functions of Mg(1-y)Ca(y)H(x) thin films (0.03 <= y <= 0.17)
2011 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 50, no 21, 3879-3884 p.Article in journal (Refereed) Published
Mg(1-y)Ca(y) (0.03 <= y <= 0.17) alloy thin films covered with thin Pd were hydrogenated using 4% H(2) in Ar under atmospheric pressure at room temperature. The complex dielectric functions (epsilon = epsilon(1) + i epsilon(2)) in the range of 0.75 to 5.0 eV of these hydrides were evaluated with spectroscopic ellipsometry. The imaginary part of the dielectric function epsilon(2) was composed of one Drude and three Lorentz oscillator terms whose peak positions were about 1.2 eV (L(1)), 2.8 eV (L(2)), and 5.2 eV (L(3)). The L(3) term observed in all hydrides is attributed to optical absorption of MgH(2) with E(g) = 5.16 eV. The Drude term, which may be due to un-hydrogenated Mg-metal, was observed in the hydrides with a low Ca composition y of less than 0.04. The L(1) term was observed in the hydrides with a Ca composition of more than 0.05, while the L(2) term was observed for more than 0.11. These L(1) and L(2) terms were estimated from a variation with hydrogenation of ellipsometric angle Psi which is due to optical absorption of CaH(2-alpha) (L(1)) and MgCaH(3.72) (L(2)). (C) 2011 Optical Society of America
Place, publisher, year, edition, pages
2011. Vol. 50, no 21, 3879-3884 p.
Other Engineering and Technologies
IdentifiersURN: urn:nbn:se:uu:diva-156950DOI: 10.1364/AO.50.003879ISI: 000292970600018OAI: oai:DiVA.org:uu-156950DiVA: diva2:435836