Formation of an r8-Dominant Si Material

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Silicon (Si) exhibits various phases under pressure.
• The rhombohedral (r8-Si) and body-centered cubic (bc8-Si) phases are formed via indentation.
• Understanding phase stability is crucial for semiconductor applications.

Purpose of the Study:

• To determine the relative volumes of r8-Si and bc8-Si in indented silicon.
• To investigate the structural changes and internal stresses within indented silicon.
• To elucidate the mechanism stabilizing the r8-Si phase.

Main Methods:

• Novel sample preparation techniques.
• X-ray diffraction for phase analysis.
• Theoretical calculations for stress and stability analysis.

Main Results:

• Quantified the relative phase volumes of r8-Si and bc8-Si.
• Observed a distorted unit cell along the indentation loading direction.
• Calculations indicated an intrinsic compression of approximately 4 GPa.

Conclusions:

• The observed intrinsic compression stabilizes the r8-Si phase in indented silicon.
• The findings provide insights into pressure-induced phase transitions in silicon.
• This work contributes to the understanding of semiconducting materials under stress.