Divacancy in 3C- and 4H-SiC : An extremely stable defect

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© 2002 American Physical Society (APS). This is the accepted version of the following article: Torpo, L. & Staab, T. E. M. & Nieminen, Risto M. 2002. Divacancy in 3C- and 4H-SiC : An extremely stable defect. Physical Review B. Volume 65, Issue 8. 085202/1-10. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.65.085202, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.65.085202.
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School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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en

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085202/1-10

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Physical Review B, Volume 65, Issue 8

Abstract

Using first-principles calculations for divacancy defects in 3C− and 4H−SiC, we determine their formation energies and stability, their ionization levels, and relaxed geometries (symmetry point groups) for neutral as well as for charged states. For 4H−SiC all four possible nearest-neighbor divacancy configurations are considered. We find not only a remarkable high binding energy of about 4 eV, but also a strong site dependence (cubic or hexagonal lattice sites) of the formation energies. Applying a Madelung-type correction to deal with the electrostatic interactions between charged supercells, our results indicate a negative-U behavior at EV+0.7 eV between the charge states 1+/1− only for nearest-neighbor divacancies on different lattice sites (mixed cubic and hexagonal) in 4H−SiC, but not for all the other cases (pure cubic or pure hexagonal) in 4H− or for the cubic divacancy in 3C−SiC.

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Torpo, L. & Staab, T. E. M. & Nieminen, Risto M. 2002. Divacancy in 3C- and 4H-SiC : An extremely stable defect. Physical Review B. Volume 65, Issue 8. 085202/1-10. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.65.085202.