Theoretical and electron paramagnetic resonance studies of hyperfine interaction in nitrogen doped 4H and 6H SiC

Szász, Krisztián; Trinh, Xuan Thang; Són, Nguyên Tiên; Janzén, Erik; Gali, Ádám

doi:10.1063/1.4866331

Cited by 22 publications

(21 citation statements)

References 26 publications

(28 reference statements)

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“…Although this cutoff provided converged structural properties and formation energies, additional tests with higher cutoffs (of up to 550 eV) were performed to examine the convergence behavior of the hyperfine parameters for neutral hydrogen. These parameters were determined within the PAW methodology [48,49] which allows the reconstruction of the all-electron wave functions inside the core regions of the nuclei.…”

Section: B Theoretical Frameworkmentioning

confidence: 99%

Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

et al. 2016

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We present a systematic study of isolated hydrogen in diverse forms of ZrO 2 (zirconia), both undoped and stabilized in the cubic phase by additions of transition-metal oxides (Y 2 O 3 , Sc 2 O 3 , MgO, CaO). Hydrogen is modeled by using muonium as a pseudoisotope in muon-spin spectroscopy experiments. The muon study is also supplemented with first-principles calculations of the hydrogen states in scandia-stabilized zirconia by conventional density-functional theory (DFT) as well as a hybrid-functional approach which admixes a portion of exact exchange to the semilocal DFT exchange. The experimentally observable metastable states accessible by means of the muon implantation allowed us to probe two distinct hydrogen configurations predicted theoretically: an oxygen-bound configuration and a quasiatomic interstitial one with a large isotropic hyperfine constant. The neutral-oxygen-bound configuration is characterized by an electron spreading over the neighboring zirconium cations, forming a polaronic state with a vanishingly small hyperfine interaction at the muon. The atom-like interstitial muonium is observed also in all samples but with different fractions. The hyperfine interaction is isotropic in calcia-doped zirconia [A iso = 3.02(8) GHz], but slightly anisotropic in the nanograin yttria-doped zirconia [A iso = 2.1(1) GHz, D = 0.13(2) GHz] probably due to muons stopping close to the interface regions between the nanograins in the latter case.

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Section: B Theoretical Frameworkmentioning

confidence: 99%

Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

et al. 2016

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“…Note that this assignment is in contrast to the previously suggested identification [16,29] that relies on a comparison of 4H and 6H -SiC magneto-optical spectra. This approach, however, can be misleading for defect configuration identification in hexagonal SiC [46].…”

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confidence: 99%

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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“…Indeed, such calculations have been helpful in the identification of point defects in different semiconductors by comparing the experimental and calculated hyperfine constants [27][28][29][30][31]. However, the nature of many ground or excited states relevant to defects and their applications are such that DFT methods deliver results of widely varying accuracy [32], meaning that great care must always be taken when this method is applied.…”

Section: Introductionmentioning

confidence: 99%

Defect states in hexagonal boron nitride: Assignments of observed properties and prediction of properties relevant to quantum computation

2018

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Theoretical and electron paramagnetic resonance studies of hyperfine interaction in nitrogen doped 4H and 6H SiC

Cited by 22 publications

References 26 publications

Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

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

Defect states in hexagonal boron nitride: Assignments of observed properties and prediction of properties relevant to quantum computation

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