Probing local atomic structure in thin films by grazing-incidence total X-ray scattering with a convergent X-ray beam.

Grazing-incidence total X-ray scattering (GI-TXS) is an important technique for evaluating the short-range order and medium-range order structures of thin films. A high-quality pair distribution function requires high-intensity total scattering data over a wide scattering vector magnitude (Q) range, which necessitates the use of high-energy X-rays. However, a lower incident angle leads to a wider footprint at the sample position, resulting in a trade-off between achieving high-intensity total scattering and using high-energy X-rays in conventional laboratory setups. In this study, we performed GI-TXS measurements on an indium tin oxide (ITO) thin film using a convergent incident X-ray beam to maximize the X-ray flux at the sample position. By incorporating the convergence angle distribution and thin film absorption parameters, the substrate contribution to the observed total scattering intensity was quantitatively estimated and corrected. As a result, the total scattering profile of the ITO thin film was successfully obtained up to Q = 21 Å-1 using a laboratory X-ray diffractometer.