Element-specific structural analysis of Si/B₄C using resonant X-ray reflectivity

Element-specific structural analysis at the buried interface of a low electron density contrast system is important in many applied fields. The analysis of nanoscaled Si/B₄C buried interfaces is demonstrated using resonant X-ray reflectivity. This technique combines information about spatial modulations of charges provided by scattering, which is further enhanced near the resonance, with the sensitivity to electronic structure provided by spectroscopy. Si/B₄C thin-film structures are studied by varying the position of B₄C in Si layers. Measured values of near-edge optical properties are correlated with the resonant reflectivity profile to quantify the element-specific composition. It is observed that, although Si/B₄C forms a smooth interface, there are chemical changes in the sputtered B₄C layer. Nondestructive quantification of the chemical changes and the spatial distribution of the constituents is reported.