Efficient method for the determination of extreme-ultraviolet optical constants in reactive materials: application to scandium and titanium

Uspenskii, Yu. A.; Seely, John F.; Popov, N. I.; Виноградов, А. В.; Pershin, Yurii P.; Кондратенко, В. В.

doi:10.1364/josaa.21.000298

Cited by 45 publications

(21 citation statements)

References 14 publications

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“…Tb in particular was found to have low absorption in the 60-70 nm range. 6 The Tb transmission data, obtained by measuring with synchrotron radiation the transmittance of Tb films of varying thickness deposited directly onto Si photodiodes, 7 are shown in Fig. 1.…”

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Terbium-based extreme ultraviolet multilayers

et al. 2005

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We have fabricated periodic multilayers that comprise either Si/Tb or SiC/Tb bilayers, designed to operate as narrowband reflective coatings near 60 nm wavelength in the extreme ultraviolet (EUV). We find peak reflectance values in excess of 20% near normal incidence. The spectral bandpass of the best Si/Tb multilayer was measured to be 6.5 nm full width at half-maximum (FWHM), while SiC/Tb multilayers have a more broad response, of order 9.4 nm FWHM. Transmission electron microscopy analysis of Si/Tb multilayers reveals polycrystalline Tb layers, amorphous Si layers, and relatively large asymmetric amorphous interlayers. Thermal annealing experiments indicate excellent stability to 100 0 C (1 h) for Si/Tb. Narrowband reflective multilayer coatings operating near normal incidence in the extreme ultraviolet (EUV) band have by now found wide application in a number of disciplines, including solar physics, photolithography, short-wavelength lasers, plasma diagnostics, etc. While peak reflectance values as high as 70% have been obtained at the short-wavelength end of the EUV near 13 nm, at longer wavelengths the performance of even the best coatings is considerably lower. The limit on multilayer performance at long wavelengths is primarily due to absorption in the constituent materials; an ideal EUV multilayer would comprise materials with low absorption so that the incident radiation can penetrate deeply into the multilayer stack, thereby allowing for the coherent addition of reflections from a large number of layer interfaces. But with high-absorption materials only a few interfaces can contribute to the reflection process, thereby limiting the ultimate performance. Our principal motivation for the development of long-wavelength EUV multilayers is directed at the production of narrowband imaging telescopes for solar physics. A number of important coronal emission lines in the 60-65 nm band, including 0 V near 63.0 nm and Mg X near 61.0 nm, could be observed if efficient narrowband multilayer coatings were available. Multilayer imagers that could be tuned to these wavelengths would nicely complement currently available multilayers that operate at shorter wavelengths, and that have been used in satellite instruments such as SoHO/EIT, 1 TRACE, 2 and the SDO/AIA 3 instrument currently under development, all of which have been limited to wavelengths shorter than 34 nm. In recent years narrowband multilayer performance has been extended to longer EUV wavelengths with materials such as Mg and Sc: SiC/Mg multilayers 4 show high reflectance in the range 25-40 nm, i.e., below the Mg K edge near 25 nm (and will be used in the SDO/AIA instrument), while Si/Sc multilayers 5 operate with relatively high efficiency in the 35-50 nm range, i.e., below the 3p-3d absorption "window" for this material. However, at wavelengths longer than -50 nm the development of efficient multilayers has been limited thus far by a dearth of suitable multilayer materials having sufficiently low absorption.We have identified the rare-earth elements, w...

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Terbium-based extreme ultraviolet multilayers

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“…The values calculated in this work were combined with the tables from the CXRO web page at energies above 1,300 eV and the measurements of Uspenski et. al 6 below 50 eV and the values given by Weaver 7 for energies from 0.1 eV to 5 eV. As a self-consistency check of the data the sum rule was calculated by integrating μ as described in previous works 8 .…”

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Measurements of the optical constants of scandium in the 50-1300eV range

et al. 2004

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Scandium containing multilayers have been produced with very high reflectivity in the soft x-ray spectrum. Accurate optical constants are required in order to model the multilayer reflectivity. Since there are relatively few measurements of the optical constants of Scandium in the soft x-ray region we have performed measurements over the energy range of 50-1,300 eV. Thin films of Scandium were deposited by ion-assisted magnetron sputtering at Linkoping University and DC Magnetron sputtering at CXRO. Transmission measurements were performed at the Advanced Light Source beamline 6.3.2. The absorption coefficient was deduced from the measurements and the dispersive part of the index of refraction was obtained using the Kramers-Kronig relation. The measured optical constants are used to model the nearnormal incidence reflectivity of Cr/Sc multilayers near the Sc L 2,3 edge.

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“…Other than In, a source of low-absorption materials in the present range has been found among lanthanides, and many of them have been fully characterized recently (La [23], Tb [9], Gd [12], Nd [12], Yb [24,25], Ce [26], Pr [27], Eu [28], Tm [29], and Dy [30] [31][32][33][34]. This relatively low absorption makes them candidates for their use in novel multilayer coatings.…”

Section: Multilayer Designmentioning

confidence: 99%

Narrowband multilayer coatings for the extreme ultraviolet range of 50-92 nm

Vidal-Dasilva¹,

Fernández-Perea²,

Méndez³

et al. 2009

Opt. Express

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Abstract:A new type of multilayer coatings with narrowband reflection properties and peaked in the ~50-92 nm spectral range has been developed. Multilayers are based on Yb, Al, and SiO films and they have been prepared by thermal evaporation. Efficient multilayers based on Yb and Al, with an SiO protective layer were prepared, but they developed a dendrite structure, which was attributed to the reactivity between Al and Yb. Multilayers based on Yb and Al, with both SiO protective and barrier layers, resulted in efficient reflective filters, with no observable dendrite growth. The peak reflectance of aged multilayers was of the order of ~0.20, with bandwidths in the range of 12 to 22 nm FWHM. in the 2-830 eV spectral range using a transmittance method, and compilation of the revised optical constants of lanthanum, terbium, neodymium, and gadolinium," Appl. ©2009 Optical Society of America

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Efficient method for the determination of extreme-ultraviolet optical constants in reactive materials: application to scandium and titanium

Cited by 45 publications

References 14 publications

Terbium-based extreme ultraviolet multilayers

Terbium-based extreme ultraviolet multilayers

Measurements of the optical constants of scandium in the 50-1300eV range

Narrowband multilayer coatings for the extreme ultraviolet range of 50-92 nm

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