Article

Analysis of Interfaces by Soft and Hard X-ray Photoemission

Surface Analysis Spotlight: XPS

	by Jia Lu Staff Scientist

As materials and devices become increasingly complex, understanding chemistry below the surface is more important than ever. Recent advances in laboratory-based hard X-ray photoelectron spectroscopy (HAXPES) are expanding the capabilities of traditional XPS, providing deeper, non-destructive insights into material composition and chemical state.

The introduction of a micro-focused, monochromated Cr Kα X-ray source enables analysis depths up to three times greater than conventional Al Kα XPS while maintaining high sensitivity for small-area measurements. By combining soft X-rays (XPS) and hard X-rays (HAXPES) within a single instrument, researchers can characterize materials from the surface through the near-bulk region without extensive sample preparation.

This complementary approach offers several advantages:

• Improved analysis of small features, such as Ti/Al flakes smaller than 100 μm, by probing beneath surface contamination to reveal accurate chemistry and stoichiometry.
• Enhanced understanding of processing effects on materials such as NiPt nanowires, where HAXPES provides a more complete view of chemical changes caused by annealing and surface treatments.
• More accurate thin-film characterization, demonstrated through thickness measurements of carbon/HfO₂/SiO₂/Si multilayers using StrataPHI modeling.
• Reduced influence of ion beam damage during depth profiling, as shown in tin oxide studies where Cr Kα measurements revealed less tin reduction than conventional XPS.

By combining XPS and HAXPES, researchers gain a powerful, non-destructive toolset for analyzing materials from the surface to the bulk. This approach delivers deeper chemical insight, improved accuracy, and greater confidence when characterizing advanced materials and next-generation devices.

To learn more about interfaces by soft and hard X-ray photoemission, please join us for Dr. Jia Lu’s poster session at AVS 72 in November.