Nanoscale elemental quantification in heterostructured SiGe nanowires.

Area of Science:

• Materials Science
• Nanotechnology
• Surface Science

Background:

• Axial heterostructured silicon-germanium (Si1-xGex) nanowires (NWs) are crucial for advanced electronic and optoelectronic devices.
• Understanding their nanoscale chemical composition is essential for device performance and fabrication.
• Scanning Auger Microscopy (SAM) offers high-resolution surface analysis capabilities.

Purpose of the Study:

• To perform nanoscale chemical characterization of axial heterostructured Si1-xGex NWs.
• To investigate axial and radial composition heterogeneities within the NWs.
• To evaluate the applicability and limitations of SAM for quantifying NW composition.

Main Methods:

• Utilized Scanning Auger Microscopy (SAM) for nanoscale chemical analysis.
• Employed local spectroscopy, line-scan, and depth profile measurements.
• Verified quantification by assessing preferential sputtering on bulk SiGe samples.

Main Results:

• Achieved sufficient lateral resolution with SAM to resolve individual Si1-xGex NWs.
• Confirmed radial growth of Germanium (Ge), forming a Ge shell around the NWs.
• Established reliable quantification for NWs >100 nm, but identified limitations for smaller NWs due to edge effects and backscattered electron contributions.

Conclusions:

• SAM is a powerful tool for the nanoscale chemical characterization of Si1-xGex NWs.
• Ge radial growth is a significant phenomenon in these heterostructured NWs.
• Quantification accuracy in SAM is size-dependent for NWs, requiring careful consideration of topographical effects for smaller structures.