Negatively charged Si vacancy in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>4</mml:mn><mml:mi>H</mml:mi></mml:math>SiC: A comparison between theory and experiment

Wimbauer, T.; Meyer, B. K.; Hofstaetter, A.; Scharmann, A.; Overhof, H.

doi:10.1103/physrevb.56.7384

Cited by 182 publications

(145 citation statements)

References 12 publications

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“…In agreement with previous theoretical estimates [28], these results disprove the existence of an undistorted T d symmetric silicon vacancy [22] in 4H -SiC, which was one of the basic assumptions of model II [14]. Furthermore, both the calculated ZPL energies and the hyperfine values are in good agreement with the experimental data.…”

supporting

confidence: 80%

“…Today, it is widely accepted that V1-V3 PL lines and T V1 -T V3 electron paramagnetic resonance (EPR) signals in 4H -and 6H -SiC are related to spin-3/2 negatively charged silicon vacancies [22][23][24][25]. On the other hand, the actual microscopic configuration of these vacancy related centers is still debated.…”

mentioning

confidence: 99%

“…The V2 line in 4H -SiC [4] and the V2 and V3 lines in 6H -SiC [13] are sufficiently strong to observe their corresponding electron spin via optically detected magnetic resonance (ODMR) measurements at room temperature. In particular, it has been demonstrated that the V2 color center in 4H -SiC can be used for magnetometer [17][18][19][20] and nanoscale thermometer [21] applications and as a room-temperature maser [14].Today, it is widely accepted that V1-V3 PL lines and T V1 -T V3 electron paramagnetic resonance (EPR) signals in 4H -and 6H -SiC are related to spin-3/2 negatively charged silicon vacancies [22][23][24][25]. On the other hand, the actual microscopic configuration of these vacancy related centers is still debated.…”

mentioning

confidence: 99%

“…We note that Mizuochi and co-workers [29] associated the V2 center particularly with V Si (−) at the h site by comparing the similarities of V1-V2 and V1-V3 signals in 4H -and 6H -SiC, respectively. Model II, on the other hand, uses the nondistorted silicon-vacancy model [14,22], where close to T d symmetry with negligible ZFS is assumed for an isolated V Si (−) in hexagonal SiC. In this model, a proximate neutral carbon vacancy in a symmetrical configuration is assumed [see, for example, the model of the V2 center in 4H -SiC [14] in Fig.…”

mentioning

confidence: 99%

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Identification of Si-vacancy related room-temperature qubits in 4H silicon carbide

et al. 2017

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The identification of a microscopic configuration of point defects acting as quantum bits is a key step in the advance of quantum information processing and sensing. Among the numerous candidates, silicon-vacancy related centers in silicon carbide (SiC) have shown remarkable properties owing to their particular spin-3/2 ground and excited states. Although, these centers were observed decades ago, two competing models, the isolated negatively charged silicon vacancy and the complex of negatively charged silicon vacancy and neutral carbon vacancy [Phys. Rev. Lett. 115, 247602 (2015)], are still argued as an origin. By means of high-precision first-principles calculations and high-resolution electron spin resonance measurements, we here unambiguously identify the Si-vacancy related qubits in hexagonal SiC as isolated negatively charged silicon vacancies. Moreover, we identify the Si-vacancy qubit configurations that provide room-temperature optical readout. DOI: 10.1103/PhysRevB.96.161114 Point defects in solids acting as quantum bits (qubits) are a highly promising platform for quantum information processing (QIP) and nanoscale sensor applications where typically their electron spin provides the functional quantum states. There are qubits that have long electron spin coherence times [1][2][3][4][5], and some of them have been demonstrated to persist up to room temperature [1,4]. These electron spins can be optically initialized and read out [2,6-9], making them very attractive candidates for QIP and related applications [10][11][12]. Among these qubits, silicon-vacancy related defects in hexagonal polytypes of SiC, such as 4H -and 6H -SiC, have shown favorable spin properties [13,14], demonstrated even at a single defect level at room temperature [4]. Two and three different silicon-vacancy related centers were observed in 4H -and 6H -SiC, where the corresponding photoluminescence (PL) lines are denoted as V1 and V2, and V1, V2, and V3, [15,16], respectively. The V2 line in 4H -SiC [4] and the V2 and V3 lines in 6H -SiC [13] are sufficiently strong to observe their corresponding electron spin via optically detected magnetic resonance (ODMR) measurements at room temperature. In particular, it has been demonstrated that the V2 color center in 4H -SiC can be used for magnetometer [17][18][19][20] and nanoscale thermometer [21] applications and as a room-temperature maser [14].Today, it is widely accepted that V1-V3 PL lines and T V1 -T V3 electron paramagnetic resonance (EPR) signals in 4H -and 6H -SiC are related to spin-3/2 negatively charged silicon vacancies [22][23][24][25]. On the other hand, the actual microscopic configuration of these vacancy related centers is still debated. The unanswered question is whether these centers are isolated silicon vacancies [V Si difference between the two models is how the observed finite zero-field splitting (ZFS) of the ground-state spin sublevels is explained. In model I, it is assumed that the C 3v symmetric crystal field, allowing nonzero ZFS [26], is strong enough t...

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supporting

confidence: 80%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Identification of Si-vacancy related room-temperature qubits in 4H silicon carbide

et al. 2017

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“…Several observations obtained from electron-spin-resonance ͑ESR͒, optically detected magnetic-resonance ͑ODMR͒, photoluminescence ͑PL͒, and electron-nuclear double-resonance ͑ENDOR͒ measurements assigned to silicon vacancy-related centers, high-spin states Sϭ1 and Sϭ3/2 have been reported. [6][7][8][9] Recently, an all-electron linear muffin-tin orbital ASA calculation for unrelaxed V Si 1Ϫ in SiC has been carried out, 10 in which a large energy separation between the lowspin (Sϭ1/2) and the high-spin (Sϭ3/2) configurations was obtained.…”

mentioning

confidence: 99%

Silicon vacancy in SiC: A high-spin state defect

Torpo

Nieminen

Laasonen

et al. 1999

Applied Physics Letters

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We report results from spin-polarized ab initio local spin-density calculations for the silicon vacancy (V Si ) in 3C-and 2H-SiC in all its possible charge states. The calculated electronic structure for SiC reveals the presence of a stable spin-aligned electron-state t 2 near the midgap. The neutral and doubly negative charge states of V Si in 3C-SiC are stabilized in a high-spin configuration with Sϭ1 giving rise to a ground state, which is a many-electron orbital singlet 3 T 1 . For the singly negative V Si , we find a high-spin ground-state 4 A 2 with Sϭ3/2. In the high-spin configuration, V Si preserves the T d symmetry. These results indicate that in neutral, singly, and doubly negative charge states a strong exchange coupling, which prefers parallel electron spins, overcomes the Jahn-Teller energy. In other charge states, the ground state of V Si has a low-spin configuration.

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Neutral Vacancies in Group-IV Semiconductors

Zywietz¹,

Furthmüller²,

Bechstedt³

1998

phys. stat. sol. (b)

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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.

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Negatively charged Si vacancy in4HSiC: A comparison between theory and experiment

Cited by 182 publications

References 12 publications

Identification of Si-vacancy related room-temperature qubits in 4H silicon carbide

Identification of Si-vacancy related room-temperature qubits in 4H silicon carbide

Silicon vacancy in SiC: A high-spin state defect

Neutral Vacancies in Group-IV Semiconductors

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