X-ray broadband Ni/SiC multilayers: improvement with W barrier layers.
We present an experimental study and performance improvement of periodic and aperiodic Ni/SiC multilayer coatings. Periodic Ni/SiC multilayer mirrors have been coated and characterized by grazing incidence X-ray reflectometry at 8.048 keV (Cu Kα radiation) and by measurements at 3 keV and 5 keV on synchrotron radiation facilities. An interdiffusion effect is found between Ni and SiC layers. A two-material model, Ni(x)Si(y)/SiC, using a silicide instead of Ni, was used to fit the measurements. The addition of 0.6 nm W barrier layers at the interfaces allows a significant reduction of the interdiffusion between Ni and SiC. In order to obtain a specific reflectivity profile in the 2 - 8 keV energy range, we have designed and coated aperiodic multilayer mirrors by using Ni/SiC with and without W barrier layers. The experimental reflectivity profiles as a function of the photon energy were measured on a synchrotron radiation facility in both cases. Adding W barrier layers in Ni/SiC multilayers provides a better precision on the layer thicknesses and a very good agreement between the experimental data and the targeted spectral profile.
B
B
Emprin
Ph
P
Troussel
G
G
Soullié
Ph
P
Stemmler
P
P
Mercère
E
E
Meltchakov
A
A
Jérôme
F
F
Delmotte
D017554:Carbon Compounds, Inorganic / Q000737:chemistry*; D008962:Models, Theoretical; D009532:Nickel / Q000737:chemistry*; D055620:Optical Phenomena; D017655:Silicon Compounds / Q000737:chemistry*; D014414:Tungsten / Q000737:chemistry*; D014965:X-Rays
D017554:Carbon Compounds, Inorganic; D017655:Silicon Compounds; D009532:Nickel; D014414:Tungsten; C022088:silicon carbide