Neutral Vacancies in Group-IV Semiconductors

Abstract

Ab initio plane-wave-supercell calculations are performed for the neutral monovacancies in silicon, silicon carbide and diamond using ultrasoft non-normconserving Vanderbilt pseudopotentials. We study the structure, the energetics and the single-particle energy spectrum. The local symmetry, the atomic displacements, and the formation energies are found to be sensitive with respect to the numerical details. The convergence of the calculations with the supercell size is demonstrated. We find a tendency for the stabilization of the tetragonal D 2d symmetry for the vacancy in Si and the C vacancy in SiC, whereas the Si vacancy in SiC and the vacancy in diamond nearly conserve the T d symmetry. The structural changes are related to the electronic defect states. Defect levels are derived for the four vacancies under consideration.

The electronic states of the neutral vacancy in diamond: a quantum mechanical approach

“…Intrinsic defects in diamond, silicon and silicon carbide have been extensively investigated both experimentally and theoretically [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The formation of a vacancy in a diamond (or zinc blend) like structure possessing T d symmetry generates four dangling bonds at the nearest neighbors.…”

Density-functional calculations of defect formation energies using supercell methods: Defects in diamond

“…16,17 Systematic formation energy calculations have been performed for several semiconductors, including Si, [18][19][20] SiC, 21,38 GaN, 22 and diamond. 14,[23][24][25] The formation energy E f of a defect with charge q is given by…”

Si-H clusters, defects, and hydrogenated silicon

“…Density functional calculations confirm the existence of Jahn-Teller distortions. However, the results show many differences in detail, 1,[3][4][5][6][7] and both the atomic arrangement and the formation energy converge extremely slowly with the size of the supercell and the number of k points in the Brillouin zone. 5 Large Jahn-Teller distortions have also been found near divacancies in crystalline Si.…”