High-Resolution Raman and Luminescence Spectroscopy of Isotope-Pure &lt;sup&gt;28&lt;/sup&gt;Si&lt;sup&gt;12&lt;/sup&gt;C, Natural and &lt;sup&gt;13&lt;/sup&gt;C – Enriched 4H-SiC

Ivanov, Ivan Gueorguiev; Yazdanfar, Milan; Lundqvist, Björn; Chen, Jr Tai; Ul-Hassan, Jawad; Stenberg, Pontus; Liljedahl, Rickard; Són, Nguyên Tiên; Ager, Joel W.; Kordina, Olof; Janzén, Erik

doi:10.4028/www.scientific.net/msf.778-780.471

Cited by 11 publications

(6 citation statements)

References 10 publications

(22 reference statements)

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“…For instance, Wopenka et al (2010) previously reported a noncubic SiC Raman spectrum for an atypically large (~30 lm) X grain (grain LU-13, also known as "Bonanza"; Zinner et al 2011). More recently, Ivanov et al (2014) showed that the Raman band positions of synthetic isotope-enriched SiC are shifted with respect to those of the same polytype but with normal (i.e., terrestrial) isotopic ratios. As the carbon, nitrogen, and silicon isotopic compositions of presolar SiC grains vary by up to several orders of magnitude, it is an intriguing possibility that there are detectable systematic shifts of Raman band positions due to isotopic substitution in presolar SiC grains.…”

Section: Introductionmentioning

confidence: 99%

Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Liu

Steele

Nittler

et al. 2017

Meteorit & Planetary Scien

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Abstract-We report the development of a novel method to nondestructively identify presolar silicon carbide (SiC) grains with high initial 26 Al/ 27 Al ratios (>0.01) and extreme 13 C-enrichments ( 12 C/ 13 C ≤ 10) by backscattered electron-energy dispersive X-ray (EDX) and micro-Raman analyses. Our survey of a large number of presolar SiC demonstrates that (1)~80% of core-collapse supernova and putative nova SiC can be identified by quantitative EDX and Raman analyses with >70% confidence; (2)~90% of presolar SiC are predominantly 3C-SiC, as indicated by their Raman transverse optical (TO) peak position and width; (3) presolar 3C-SiC with 12 C/ 13 C ≤ 10 show lower Raman TO phonon frequencies compared to mainstream 3C-SiC. The downward shifted phonon frequencies of the 13 C-enriched SiC with concomitant peak broadening are a natural consequence of isotope substitution. 13C-enriched SiC can therefore be identified by micro-Raman analysis; (4) larger shifts in the Raman TO peak position and width indicate deviations from the ideal 3C structure, including rare polytypes. Coordinated transmission electron microscopy analysis of one X and one mainstream SiC grain found them to be of 6H and 15R polytypes, respectively; (5) our correlated Raman and NanoSIMS study of mainstream SiC shows that high nitrogen content is a dominant factor in causing mainstream SiC Raman peak broadening without significant peak shifts; and (6) we found that the SiC condensation conditions in different stellar sites are astonishingly similar, except for X grains, which often condensed more rapidly and at higher atmospheric densities and temperatures, resulting in a higher fraction of grains with much downward shifted and broadened Raman TO peaks.

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Section: Introductionmentioning

confidence: 99%

Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Liu

Steele

Nittler

et al. 2017

Meteorit & Planetary Scien

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“…The starting material used in this study is isotopically purified 4H- 28 SiC epilayer grown by chemical vapor deposition (CVD) [31]. The isotope purity of 28 Si in this layer is expected to be 99.85%, which is the value determined by secondary ion mass spectrometry (SIMS) for other isotopically enriched 4H-28 Si 12 C wafers grown in the series [32].…”

Section: Methodsmentioning

confidence: 99%

Ligand hyperfine interactions at silicon vacancies in 4H-SiC

Són

Stenberg

Jokubavičius

et al. 2019

J. Phys.: Condens. Matter

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become known to be very weak compared to the central line (CL) of this S = 3/2 center. Therefore, the V − Si center in hexagonal polytypes was believed to give rise to only one EPR line like the center in the cubic crystal 3C-SiC with no ZFS [3]. We refer to this defect as the no-ZFS V − Si center. Later optically detected magnetic resonance (ODMR) studies reported several ODMR centers with axial symmetry and small ZFS, labelled T V1a , T V2a , T V1b and T V2b , which were suggested to be related to the V1 and V2 photoluminescence (PL) lines at 1. 438 and 1.352 eV, respectively,. The absence of the CL in the ODMR spectra measured under resonant excitation led to the assignment of these centers to the isolated neutral Si vacancy (V 0 Si ) with spin S = 1 [4]. Two PL centers are expected for two possible configurations

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“…We showed that the coherence time of the divacancy in our naturally isotopic, semi-insulating 4H-SiC is 1.3 ms. In principle, the 29 Si or 13 C nuclei can be removed by isotopic purification, which is available in SiC 56,57 , and a longer qubit coherence time could be achieved 12,18,24,58 . In Fig.…”

Section: Isotopic Purification To Lengthen Tmentioning

confidence: 99%

Quantum decoherence dynamics of divacancy spins in silicon carbide

et al. 2016

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Long coherence times are key to the performance of quantum bits (qubits). Here, we experimentally and theoretically show that the Hahn-echo coherence time of electron spins associated with divacancy defects in 4H–SiC reaches 1.3 ms, one of the longest Hahn-echo coherence times of an electron spin in a naturally isotopic crystal. Using a first-principles microscopic quantum-bath model, we find that two factors determine the unusually robust coherence. First, in the presence of moderate magnetic fields (30 mT and above), the 29Si and 13C paramagnetic nuclear spin baths are decoupled. In addition, because SiC is a binary crystal, homo-nuclear spin pairs are both diluted and forbidden from forming strongly coupled, nearest-neighbour spin pairs. Longer neighbour distances result in fewer nuclear spin flip-flops, a less fluctuating intra-crystalline magnetic environment, and thus a longer coherence time. Our results point to polyatomic crystals as promising hosts for coherent qubits in the solid state.

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High-Resolution Raman and Luminescence Spectroscopy of Isotope-Pure <sup>28</sup>Si<sup>12</sup>C, Natural and <sup>13</sup>C – Enriched 4H-SiC

Cited by 11 publications

References 10 publications

Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Coordinated EDX and micro‐Raman analysis of presolar silicon carbide: A novel, nondestructive method to identify rare subgroup SiC

Ligand hyperfine interactions at silicon vacancies in 4H-SiC

Quantum decoherence dynamics of divacancy spins in silicon carbide

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