Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
Synchrotron Utilisation Section, Raja Ramnna Centre for Advanced Technology, Indore 752013, India.
Phys Chem Chem Phys. 2023 Jan 27;25(4):3072-3082. doi: 10.1039/d2cp03785h.
The optical performance of low-bilayer-thickness metallic multilayers (ML) can be improved significantly by limiting the intermixing of consecutive layers at the interfaces. Barrier layers are supposed to exhibit a decisive role in controlling diffusion across the interfaces. The element-specific grazing incidence extended X-ray absorption fine structure technique using synchrotron radiation has been used in conjunction with grazing incidence X-ray reflectivity and diffuse X-ray scattering measurements to study the impact of the two most common barrier layers, , C and BC, at the interfaces of Cr/Sc MLs. The diffusion propagation is reduced by both the barrier layers; however, it is found that the improvement is more significant with the BC barrier layer. It is seen that C forms an intermixed layer with Sc and leads to carbide formation at the interface, which then acts as shielding and prevents further interdiffusion, while BC hardly penetrates into Sc and stops the overlap between Sc and Cr directly by wetting the corresponding interface. Thus, the above measurements reveal crucial and precise information regarding the elemental diffusion kinetics at the interfaces of Cr/Sc MLs in a non-destructive way, which is very important for technological applications of these MLs as X-ray optical devices.
通过限制界面处相邻层之间的混合，可以显著提高低双层厚度金属多层（ML）的光学性能。阻挡层应该在控制界面处的扩散方面发挥决定性作用。已经使用同步辐射的元素特定掠入射扩展 X 射线吸收精细结构技术与掠入射 X 射线反射率和漫散射 X 射线散射测量相结合，研究了两种最常见的阻挡层（C 和 BC）在 Cr/Sc ML 界面处的影响。两种阻挡层都可以减少扩散传播；然而，发现 BC 阻挡层的改善更为显著。可以看出，C 与 Sc 形成混合层，并在界面处形成碳化物，然后作为屏蔽层，防止进一步的互扩散，而 BC 几乎不会渗透到 Sc 中，并通过润湿相应的界面直接阻止 Sc 和 Cr 之间的重叠。因此，上述测量以非破坏性方式揭示了 Cr/Sc ML 界面处元素扩散动力学的关键和精确信息，这对于这些 ML 作为 X 射线光学器件的技术应用非常重要。
