Determining pair distribution functions of thin films using laboratory-based X-ray sources.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Accurate structural characterization of thin amorphous films is crucial for understanding their properties.
• Traditional X-ray diffraction methods often struggle with the weak scattering signals from thin films and interference from substrates.

Purpose of the Study:

• To demonstrate a feasible method for obtaining accurate pair distribution functions (PDFs) of thin amorphous films.
• To enable nanoscale structural analysis using readily available laboratory X-ray sources.

Main Methods:

• Utilizing modern laboratory-based X-ray sources for diffraction.
• Employing a single diffraction scan approach, avoiding separate substrate or air scans.
• Using a crystalline substrate with oblique scattering geometry to minimize Bragg scattering.
• Applying a discriminating energy filter to reduce Compton scattering.
• Systematic pixel selection and 3D-printed sample holders to minimize extraneous scattering.
• Incorporating a theoretical tool to account for X-ray optical effects and intensity ratios.

Main Results:

• Accurate pair distribution functions were obtained for thin amorphous films down to 80 nm thickness.
• Substrate Bragg scattering was effectively minimized by using oblique scattering geometry.
• Compton scattering from the substrate was significantly reduced using an energy filter.
• Scattering from the sample holder and air was minimized through optimized experimental design.

Conclusions:

• The demonstrated method is feasible for accurate structural analysis of thin amorphous films using laboratory X-ray sources.
• This technique simplifies the experimental procedure by requiring only a single diffraction scan.
• The approach provides a powerful tool for nanoscale materials characterization and research.