Quantification of the Void Volume in Single-Crystal Silicon

Area of Science:

• Materials Science
• Nuclear Physics
• Metrology

Background:

• Accurate characterization of defects in silicon is crucial for advanced materials and metrology.
• Determining the concentration of vacancies is essential for precise measurements, such as the Avogadro constant.
• Existing methods may have limitations in sensitivity or applicability to high-purity silicon.

Purpose of the Study:

• To investigate a new method for quantifying void volume in silicon single crystals.
• To develop and validate a protocol for using copper decoration and neutron activation analysis (NAA).
• To assess the method's suitability for setting upper limits on vacancy concentrations in silicon used for Avogadro constant determination.

Main Methods:

• Utilized copper (Cu) decoration to highlight voids within the silicon matrix.
• Employed neutron activation analysis (NAA) for sensitive elemental quantification.
• Developed a measurement protocol tested on a high-purity natural silicon sample (5 cm³, 10 g).

Main Results:

• Successfully applied the Cu decoration and NAA method to a silicon sample.
• Achieved a few percent uncertainty in Cu concentration determination at the 10¹⁴ cm⁻³ level.
• Demonstrated the method's potential for precise void volume assessment.

Conclusions:

• The developed method is a viable candidate for measuring void volumes in silicon.
• The technique's precision supports its application in setting upper limits for vacancy concentrations.
• This contributes to improving the accuracy of the Avogadro constant determination.