Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling...

Area of Science:

• Materials Science
• Nuclear Physics
• Surface Science

Background:

• Accurate hydrogen depth profiling is crucial for understanding material properties.
• Existing methods may lack the required sensitivity or depth resolution.
• Nuclear Reaction Analysis (NRA) offers a non-destructive approach for quantitative hydrogen analysis.

Purpose of the Study:

• To demonstrate the effectiveness of resonant (1)H((15)N,αγ)(12)C Nuclear Reaction Analysis (NRA) for hydrogen depth profiling.
• To showcase the technique's capability in analyzing hydrogen distribution at surfaces, interfaces, and in bulk materials.
• To present quantitative measurements of hydrogen in specific material systems.

Main Methods:

• Utilized a 6.385 MeV (15)N ion beam for resonant NRA.
• Employed the (1)H((15)N,αγ)(12)C reaction for specific detection of the (1)H isotope.
• Achieved depth profiling up to ~2 μm with varying depth resolution (sub-nm to 5 nm) based on incidence angle.

Main Results:

• Demonstrated high sensitivity for surface hydrogen coverage (~10^13 cm⁻²) and bulk concentration (~10^18 cm⁻³).
• Successfully quantified hydrogen in a H2-exposed Pd(110) single crystal.
• Determined hydrogen depth profiles at SiO2/Si interfaces with high resolution.

Conclusions:

• Resonant (1)H((15)N,αγ)(12)C NRA is a powerful, quantitative, and non-destructive method for hydrogen depth profiling.
• The technique is versatile for various vacuum-compatible materials with smooth surfaces.
• NRA, especially combined with UHV techniques, is ideal for analyzing hydrogen in advanced materials and nanostructures.