Asymmetric split-vacancy defects in SiC polytypes: a combined theoretical and electron spin resonance study

Area of Science:

• Materials Science
• Solid State Physics
• Computational Chemistry

Background:

• Silicon carbide (SiC) is a crucial semiconductor material with diverse polytypes.
• Understanding transition metal defects is vital for optimizing SiC properties.
• Ab initio calculations offer a powerful tool for defect characterization.

Purpose of the Study:

• To investigate the behavior and formation of transition metal defects in various SiC polytypes.
• To characterize the structure of asymmetric split-vacancy (ASV) complexes.
• To determine the polytype-specific detectability of these defects.

Main Methods:

• Utilizing ab initio supercell calculations to model defect structures.
• Employing density functional theory (DFT) for electronic structure analysis.
• Correlating computational findings with experimental electron spin resonance (ESR) data.

Main Results:

• Identified asymmetric split-vacancy (ASV) complexes as a key defect type.
• ASV complexes exhibit preferential site occupation in hexagonal SiC polytypes.
• These ASV defects may be undetectable in cubic SiC polytypes.
• Experimental ESR confirmed ASV complex presence in niobium-doped 4H-SiC.

Conclusions:

• The study elucidates the polytype-dependent nature of transition metal defects in SiC.
• ASV complexes represent a significant defect with implications for SiC electronic properties.
• Computational and experimental methods combined provide robust defect identification.