Fig. 2. (a) X-ray reflection, refraction, and absorption when X-rays of wavevector ${\overrightarrow{k}}_i$ incident on the surface of a thick substrate. n₀ and n₁ are refractive indices of air and substrate, respectively, and σ is the surface roughness of the substrate. Reflection occurs when θ_i = θ_f, and refraction follows Snell’s law as explained in the text. Additionally, photoelectrons (PE), fluorescence (FL), and heat are generated when incident X-rays are absorbed by the medium. (b) Calculated (left) X-ray reflectivity patterns and (right) SLD (scattering length density) profiles of a thick LaAlO₃ substrate. The X-ray energy was set to 10 keV and the roughness of the surface was set to 0 (black) and 3 Å (red). (c) Reflection of a single slab. n₀, n₁ and n_∞ are refractive indices of air, slab, and substrate, respectively. σ₁ and σ_∞ are roughness between air and slab, and between slab and substrate, respectively. (d) Calculated X-ray reflectivity patterns of SrTiO₃(10 nm)/LaAlO₃ systems. Two films have surface roughness with σ₁ = 3 and 7 Å, and all σ_∞ are fixed at 3 Å. And two X-ray energies are considered to see the anomalous effect on δ (density-related value) of SrTiO₃ film. One at 10 keV (black, red) and the other at 16.2 keV (blue), slightly above the Sr K absorption edge. (Left) Calculated reflectivity patterns and (right) SLD profiles. In SLD profiles, * indicates LaAlO₃. All reflectivity patterns were calculated using the Refnx program [13].

Applied Science and Convergence Technology 2022;31:128~132 https://doi.org/10.5757/ASCT.2022.31.6.128

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