Density-functional study of atomic and electronic structures of multivacancies in silicon carbide

Iwata, Junichi; Shinei, Chikara; Oshiyama, Atsushi

doi:10.1103/physrevb.93.125202

Cited by 20 publications

(11 citation statements)

References 81 publications

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“…While the overall shape of the curves calculated with the PBE and the HSE functional is similar, the location of the charge transition levels depends on the density functional and the charge correction scheme employed [35,36,40,41]. As observed previously [35], the defect formation energy of the neutral relative to the charged defects is predicted to be larger with the HSE functional than with the PBE functional. This results in an increased stability range of the positive charge state when the presumably more accurate HSE functional is used.…”

Section: Defect Formation Energiessupporting

confidence: 59%

“…In particular, the calculation of hyperfine tensors enables comparison between computational and electron paramagnetic resonance results facilitating experimental assignment [17][18][19][30][31][32][33][34]. Defect formation energies as a function of the Fermi level have been computed [20,30,[34][35][36][37][38] to determine charge state stabilities and transition levels. Evaluation of excited states for defects in 4H-SiC have been focused on first excited states and corresponding ZPLs, which have been calculated for the NV center [12,20,39,40] and for the neutral divacancy defect using constrained DFT [12,39,41].…”

Section: Introductionmentioning

confidence: 99%

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Charge state switching of the divacancy defect in 4H -SiC

et al. 2018

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Optical charge state switching was previously observed in photoluminescence experiments for the divacancy defect in 4H-SiC. The participating dark charge state could not be identified with certainty. We use constrained DFT to investigate the mechanism of charge state conversion from the bright neutral charge state of the divacancy defect to the positive and negative charge states including corresponding recovery of the neutral charge state. While we can confirm that the positive charge state is dark, we do not find evidence that the negative charge state is dark.We compute similar absorption energies required for conversion of the neutral defect to both charge states. However, the formation of the positive charge state requires a series of excitations involving a 2-photon excitation, while the creation of the negative charge state is achieved through a single 2-photon process. Calculated absorption energies for the recovery of the neutral defect from the positive charge state fit the experimental value better than from the negative charge state. Defect formation energies as a function of the Fermi energy show a very small Fermi energy range in which the negative charge state is most stable, while the positive charge state exhibits a wide stability range. Overall, our computational results give more support to the identification of the dark charge state as the positive over the negative charge state in the mechanism of optical charge state switching.

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Section: Defect Formation Energiessupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Charge state switching of the divacancy defect in 4H -SiC

et al. 2018

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“…While the µ P was calculated using the converged energy of P body centered cube (BCC) structure, the µ Al was calculated using the Al face centered cube structure (as the total energy per number of Al atom). Our calculation which is in agreement with literature [61,62,63] shown that under equilibrium conditions, the V C and V Si are energetically favourable with respect to their formation energies under Si-rich and C-rich conditions, respectively. As a result, the formation energies of the vacancy-complexes formed with V C and V Si were obtained under Si-rich and C-rich conditions, respectively, which is also in agreement with literature [64,65]).…”

Section: Computational Detailssupporting

confidence: 92%

Induced defect levels of P and Al vacancy-complexes in 4H-SiC: A hybrid functional study

Igumbor

Olaniyan

Mapasha

et al. 2019

Materials Science in Semiconductor Processing

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“…While the chemical potentials of Si and C, that is the µ bulk Si and µ bulk C were respectively calculated using the bulk silicon and diamond (as the small difference in the energy of diamond and graphite introduced less significant error) structure respectively, the µ bulk SiC was calculated using the hexagonal cubic structure. [38,39,40]. In our calculations, the formation energies of the defect-complexes formed with V C and V Si were obtained under Si-rich and C-rich conditions, respectively, which are in agreement with literature [41,42].…”

Section: Electrically Active Induced Energy Levels and Metastability supporting

confidence: 90%

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

Igumbor¹,

Olaniyan²,

Mapasha³

et al. 2018

J. Phys.: Condens. Matter

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Electrically active induced energy levels in semiconductor devices could be beneficial to the discovery of an enhanced p or n-type semiconductor. Nitrogen (N) implanted into 4H-SiC is a high energy process that produced high defect concentrations which could be removed during dopant activation annealing. On the other hand, boron (B) substituted for silicon in SiC causes a reduction in the number of defects. This scenario leads to a decrease in the dielectric properties and induced deep donor and shallow acceptor levels. Complexes formed by the N, such as the nitrogen-vacancy centre, have been reported to play a significant role in the application of quantum bits. In this paper, results of charge states thermodynamic transition level of the N and B vacancy-complexes in 4H-SiC are presented. We explore complexes where substitutional N[Formula: see text]/N[Formula: see text] or B[Formula: see text]/B[Formula: see text] sits near a Si (V[Formula: see text]) or C (V[Formula: see text]) vacancy to form vacancy-complexes (N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text]). The energies of formation of the N related vacancy-complexes showed the N[Formula: see text]V[Formula: see text] to be energetically stable close to the valence band maximum in its double positive charge state. The N[Formula: see text]V[Formula: see text] is more energetically stable in the double negative charge state close to the conduction band minimum. The N[Formula: see text]V[Formula: see text] on the other hand, induced double donor level and the N[Formula: see text]V[Formula: see text] induced a double acceptor level. For B related complexes, the B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text] were energetically stable in their single positive charge state close to the valence band maximum. As the Fermi energy is varied across the band gap, the neutral and single negative charge states of the B[Formula: see text]V[Formula: see text] become more stable at different energy levels. B and N related complexes exhibited charge state controlled metastability behaviour.

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Density-functional study of atomic and electronic structures of multivacancies in silicon carbide

Cited by 20 publications

References 81 publications

Charge state switching of the divacancy defect in 4H -SiC

Charge state switching of the divacancy defect in 4H -SiC

Induced defect levels of P and Al vacancy-complexes in 4H-SiC: A hybrid functional study

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

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