Asymmetric Split-Vacancy Defects in SiC Polytypes: A Combined Theoretical and Electron Spin Resonance Study

Ivády, Viktor; Gällström, Andreas; Són, Nguyên Tiên; Janzén, Erik; Gali, Ádám

doi:10.1103/physrevlett.107.195501

Cited by 25 publications

(40 citation statements)

References 34 publications

(29 reference statements)

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“…1). Apparently, the number of optical centers corresponds to the number of inequivalent hexagonal sites in the unit cell of each polytype, in agreement with the theoretical expectation that Nb prefers the ASV h-h configuration (at hexagonal site) in these three polytypes [16].…”

Section: A Photoluminescence Signature Of Nb In 4h- 6h- and 15r-sicsupporting

confidence: 68%

“…Thus, this configuration (denoted hereafter as ASV h-h) is expected to form in significantly larger concentrations than any other. Electron spin resonance (ESR) measurements are consistent with the ASV h-h configuration for the case of Nb-doped 4H-SiC [16] (more details on the ESR spectra are presented in [17]). The observed ESR spectrum clearly shows the hyperfine interaction of an S = 1/2 spin with two Si atoms, demonstrating also the Jahn-Teller distortion to C 1h symmetry, in accord with the calculation.…”

Section: Introductionmentioning

confidence: 54%

“…In a recent work [16], new theoretical results on transition metal incorporation in SiC were published. Several transition metals from the first, second, and third rows of the periodic table (Ti, V, Cr, Nb, Mo, and W) are considered in this work, and first-principles calculations have been carried out for two possible configurations of the defect: pure substitutional on Si site (denoted as M Si , where M is the corresponding transition metal), and the so-called asymmetric split-vacancy (ASV) configuration which can be denoted M Si − V C , where V C denotes the carbon vacancy.…”

Section: Introductionmentioning

confidence: 99%

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Optical properties and Zeeman spectroscopy of niobium in silicon carbide

et al. 2015

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The optical signature of niobium in the low-temperature photoluminescence spectra of three common polytypes of SiC (4H, 6H, and 15R) is observed and confirms the previously suggested concept that Nb occupies preferably the Si-C divacancy with both Si and C at hexagonal sites. Using this concept we propose a model considering a Nb-bound exciton, the recombination of which is responsible for the observed luminescence. The exciton energy is estimated using first-principles calculation and the result is in very good agreement with the experimentally observed photon energy in 4H SiC at low temperature. The appearance of six Nb-related lines in the spectra of the hexagonal 4H and 6H polytypes at higher temperatures is tentatively explained on the grounds of the proposed model and the concept that the Nb center can exist in both C 1h and C 3v symmetries. The Zeeman splitting of the photoluminescence lines is also recorded in two different experimental geometries and the results are compared with theory based on phenomenological Hamiltonians. Our results show that Nb occupying the divacancy at the hexagonal site in the studied SiC polytypes behaves like a deep acceptor.

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Section: A Photoluminescence Signature Of Nb In 4h- 6h- and 15r-sicsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

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Optical properties and Zeeman spectroscopy of niobium in silicon carbide

et al. 2015

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“…N vacancies in w-AlN and C vacancies in 4H-SiC. Such pairing was previously investigated for Nb in SiC 38 and Ce in AlN 39 .…”

Section: Introductionmentioning

confidence: 82%

Designing defect-based qubit candidates in wide-gap binary semiconductors for solid-state quantum technologies

Seo

Govoni

et al. 2017

Phys. Rev. Materials

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The development of novel quantum bits is key to extend the scope of solid-state quantum information science and technology. Using first-principles calculations, we propose that large metal ionvacancy complexes are promising qubit candidates in two binary crystals: 4H-SiC and w-AlN. In particular, we found that the formation of neutral Hf-and Zr-vacancy complexes is energetically favorable in both solids; these defects have spin-triplet ground states, with electronic structures similar to those of the diamond NV center and the SiC di-vacancy. Interestingly, they exhibit different spin-strain coupling characteristics, and the nature of heavy metal ions may allow for easy defect implantation in desired lattice locations and ensure stability against defect diffusion. In order to support future experimental identification of the proposed defects, we report predictions of their optical zero-phonon line, zero-field splitting and hyperfine parameters. The defect design concept identified here may be generalized to other binary semiconductors to facilitate the exploration of new solid-state qubits.

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“…In the hexagonal 4H-SiC there are two different possible sites of simple point defects, like V Si , known as h and k [80]. The electronic structures of these sites are approximately the same, therefore we only consider the h site in the following.…”

Section: V Si In 4h-sicmentioning

confidence: 99%

Theoretical unification of hybrid-DFT andDFT + Umethods for the treatment of localized orbitals

et al. 2014

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Hybrid functionals serve as a powerful practical tool in different fields of computational physics and quantum chemistry. On the other hand, their applicability for the case of correlated d and f orbitals is still questionable and needs more considerations. In this article we formulate the on-site occupation dependent exchange correlation energy and effective potential of hybrid functionals for localized states and connect them to the on-site correction term of the DFT + U method. The resultant formula indicates that the screening of the onsite electron repulsion is governed by the ratio of the exact exchange in hybrid functionals. Our derivation provides a theoretical justification for adding a DFT + U -like on-site potential in hybrid-DFT calculations to resolve issues caused by overscreening of localized states. The resulting scheme, hybrid DFT + V w , is tested for chromium impurity in wurtzite AlN and vanadium impurity in 4H-SiC, which are paradigm examples of systems with different degrees of localization between host and impurity orbitals.

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Asymmetric Split-Vacancy Defects in SiC Polytypes: A Combined Theoretical and Electron Spin Resonance Study

Cited by 25 publications

References 34 publications

Optical properties and Zeeman spectroscopy of niobium in silicon carbide

Optical properties and Zeeman spectroscopy of niobium in silicon carbide

Designing defect-based qubit candidates in wide-gap binary semiconductors for solid-state quantum technologies

Theoretical unification of hybrid-DFT andDFT + Umethods for the treatment of localized orbitals

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