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Interface study of a high‐performance W/B 4 C X‐ray mirror
Author(s) -
Siffalovic Peter,
Jergel Matej,
Chitu Livia,
Majkova Eva,
Matko Igor,
Luby Stefan,
Timmann Andreas,
Roth Stephan Volker,
Keckes Jozef,
Maier Guenter Alois,
Hembd Alexandra,
Hertlein Frank,
Wiesmann Joerg
Publication year - 2010
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889810036782
Subject(s) - materials science , scattering , amorphous solid , grazing incidence small angle scattering , surface finish , annealing (glass) , crystallite , optics , analytical chemistry (journal) , condensed matter physics , crystallography , physics , chemistry , composite material , small angle neutron scattering , neutron scattering , metallurgy , chromatography
A high‐performance W/B 4 C multilayer mirror with 80 periods of nominally 1.37 nm was measured by grazing‐incidence small‐angle X ray scattering (GISAXS) in order to analyse the lateral and vertical correlations of the interface roughness within the framework of a scaling concept of multilayer growth. A dynamic growth exponent z = 2.19 (7) was derived, which is close to the value predicted by the Edwards–Wilkinson growth model. The effective number of correlated periods indicates a partial replication of the low interface roughness frequencies. A simulation of the GISAXS pattern based on the Born approximation suggests a zero Hurst fractal parameter H and a logarithmic type of autocorrelation function. The as‐deposited mirror layers are amorphous and exhibit excellent thermal stability up to 1248 K in a 120 s rapid thermal vacuum annealing process. At higher temperatures, the B 4 C layers decompose and poorly developed crystallites of a boron‐rich W–B hexagonal phase are formed, and yet multilayer collapse is not complete even at 1273 K. Ozone treatment for 3000 s in a reactor with an ozone concentration of 150 mg m −3 results in the formation of an oxidized near‐surface region of a thickness approaching ∼10% of the total multilayer thickness, with a tendency to saturation.