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Proceedings Paper

Optical properties and application of uranium-based thin films for the extreme ultraviolet and soft x-ray region
Author(s): Richard L. Sandberg; David D. Allred; Shannon Lunt; Marie K. Urry; R. Steven Turley
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Paper Abstract

Uranium oxide and uranium nitride thin films reflect significantly more than all previously known/standard reflectors (e.g., nickel, gold, and iridium) for most of the 4-10 nm range at low angles of incidence. This work includes measurements of the EUV/soft x-ray (2-20 nm) reflectance of uranium-based thin films (~20 nm thick) and extraction of their optical constants (δ and β). We report the reflectances at 5, 10, and 15 degrees grazing incidence of air-oxidized sputtered uranium, reactively sputtered (O2) uranium oxide, and reactively sputtered (N2) uranium nitride thin films measured at Beamline 6.3.2 at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL). Additionally, we report optical constants of reactively sputtered uranium oxide at nine wavelengths from 4.6 to 17.5 nm derived from ALS angle-scan reflectance measurements. We also report optical constants of uranium nitride at 13 and 14 nm. We compare the reflectance of these uranium-compound thin films to gold, nickel (and nickel oxide), and iridium thin films from 2.5 to 11.6 nm. These metal thin films were chosen for comparison due to their wide use in EUV/soft x-ray applications as low-angle, thin-film reflectors. The uranium compounds can exhibit some surface oxidation in ambient air. There are important discrepancies between UO2’s and UN’s actual thin-film reflectance with those predicted from tabulated optical constants of the elemental constituents of the compounds. These differences are also demonstrated in the optical constants we report. Uranium-based optics applications have important advantages for zone plates, thin-film reflectors, and filters.

Paper Details

Date Published: 14 October 2004
PDF: 12 pages
Proc. SPIE 5538, Optical Constants of Materials for UV to X-Ray Wavelengths, (14 October 2004); doi: 10.1117/12.560717
Show Author Affiliations
Richard L. Sandberg, Brigham Young Univ. (United States)
David D. Allred, Brigham Young Univ. (United States)
Shannon Lunt, Brigham Young Univ. (United States)
Marie K. Urry, Brigham Young Univ. (United States)
R. Steven Turley, Brigham Young Univ. (United States)

Published in SPIE Proceedings Vol. 5538:
Optical Constants of Materials for UV to X-Ray Wavelengths
Regina Soufli; John F. Seely, Editor(s)

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