X-ray broadband Ni/SiC multilayers: improvement with W barrier layers

Area of Science:

• Materials Science
• Nanotechnology
• X-ray Optics

Background:

• Multilayer coatings are crucial for X-ray optics.
• Nickel/Silicon Carbide (Ni/SiC) multilayers are widely used but suffer from interdiffusion.
• Interdiffusion degrades coating performance and limits applications.

Purpose of the Study:

• To investigate and improve the performance of periodic and aperiodic Ni/SiC multilayer coatings.
• To mitigate interdiffusion between Ni and SiC layers.
• To achieve specific reflectivity profiles for X-ray applications.

Main Methods:

• Coating of periodic and aperiodic Ni/SiC multilayer mirrors.
• Characterization using grazing incidence X-ray reflectometry (GIXR) and synchrotron radiation.
• Analysis using a two-material model incorporating silicide formation.
• Introduction of tungsten (W) barrier layers at interfaces.

Main Results:

• Observed significant interdiffusion between Ni and SiC layers.
• Demonstrated that 0.6 nm W barrier layers effectively reduce Ni-SiC interdiffusion.
• Designed and coated aperiodic multilayers with and without W barriers.
• Achieved precise layer thicknesses and excellent agreement with targeted spectral profiles using W barriers.

Conclusions:

• Tungsten barrier layers significantly reduce interdiffusion in Ni/SiC multilayers.
• The use of W barriers enables precise control over multilayer structure and optical properties.
• Improved Ni/SiC multilayers with W barriers are suitable for advanced X-ray optics requiring specific reflectivity profiles.