Formation and properties of defects and small vacancy clusters in SiC: Ab initio calculations

Journal Article · Fri Sep 11 04:00:00 EDT 2009 · Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 267(18):2995-2998

DOI:https://doi.org/10.1016/j.nimb.2009.06.018· OSTI ID:965542

Gao, Fei; Weber, William J; Xiao, H Y; Zu, Xiaotao T

Large-scale ab initio simulation methods have been employed to investigate the configurations and properties of defects in SiC. Atomic structures, formation energies and binding energies of small vacancy clusters have also been studied as a function of cluster size, and their relative stabilities are determined. The calculated formation energies of point defects are in good agreement with previously theoretical calculations. The results show that the most stable configuration of a di-vacancy cluster consists of two C vacancies located at second nearest neighbor sites, while a di-vacancy with two Si vacancies is not stable and may dissociate at room temperature. In general, the formation energies of small vacancy clusters increase with size, but the formation energies for clusters with a Si vacancy and n C vacancies (VSi-nVC) are much smaller than those with a C vacancy and n Si vacancies (VC-nVSi). These results demonstrate that the VSi-nVC clusters are more stable than the VC-nVSi clusters in SiC, and provide possible nucleation sites for larger vacancy clusters or voids to grow. For these small vacancy clusters, the binding energy decreases with increasing cluster size, and ranges from 2.5 to 4.6 eV. These results indicate that the small vacancy clusters in SiC are stable at temperatures up to 1900 K, which is consistent with experimental observations.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 965542
• Report Number(s): PNNL-SA-67046; 25682; 34899; KC0201020
• Journal Information: Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 267(18):2995-2998, Journal Name: Nuclear Instruments and Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms, 267(18):2995-2998 Journal Issue: 18 Vol. 267
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Ab initio simulation
BINDING ENERGY
COMPUTERIZED SIMULATION
Defect Clusters
Defect Properties
Environmental Molecular Sciences Laboratory
FORMATION HEAT
POINT DEFECTS
SILICON CARBIDES
STABILITY
Silicon Carbide
VACANCIES