Structure and energetics of carbon-related defects in SiC (0001)/SiO$_{\rm 2}$ systems revealed by first-principles calculations: Defects in SiC, SiO$_{\rm 2}$, and just at their interface

TL;DR

This study uses first-principles calculations to analyze the atomic structures, stability, and energy levels of carbon-related defects in SiC/SiO2 systems, revealing how oxidation conditions influence defect positions and stability.

Contribution

It provides new insights into the stable configurations and energetics of carbon defects in SiC/SiO2 interfaces under different oxidation environments using first-principles methods.

Findings

Di-carbon antisite ((C2)Si) is stable in SiC under O-rich conditions.

Si-C-C-Si defect at the interface is critical under O-poor conditions.

High-temperature O-poor oxidation reduces defect formation, aligning with experimental data.

Abstract

We report first-principles calculations that reveal the atomic forms, stability, and energy levels of carbon-related defects in SiC (0001)/SiO$_{\rm 2}$ systems. We clarify the stable position (SiC side, SiO$_{\rm 2}$ side, or just at the SiC/SiO$_{\rm 2}$ interface) of defects depending on the oxidation environment. Under an O-rich condition, the di-carbon antisite ((C$_{\rm 2}$)$_{\rm Si}$) in the SiC side is stable and critical for $n$-channel MOSFETs, whereas the di-carbon defect (Si-C-C-Si) at the interface becomes critical under an O-poor condition. Our results suggest that the oxidation of SiC under a high-temperature O-poor condition is favorable in reducing the defects, in consistent with recent experimental reports.