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| 2. |
- Trinh, Xuan Thang, et al.
(författare)
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Identification of the negative carbon vacancy at quasi-cubic site in 4H-SiC by EPR and theoretical calculations
- 2014
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Ingår i: Silicon Carbide and Related Materials 2013, PTS 1 AND 2. - : Trans Tech Publications Inc.. ; , s. 285-288
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Konferensbidrag (refereegranskat)abstract
- In freestanding n-type 4H-SiC epilayers irradiated with low-energy (250 keV) electrons at room temperature, the electron paramagnetic resonance (EPR) spectrum of the negative carbon vacancy at the hexagonal site, V-C(-)(h), and a new signal were observed. From the similarity in defect formation and the spin-Hamiltonian parameters of the two defects, the new center is suggested to be the negative C vacancy at the quasi-cubic site, V-C(-)(k). The identification is further supported by hyperfine calculations.
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| 3. |
- Trinh, Xuan Thang, et al.
(författare)
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Negative-U carbon vacancy in 4H-SiC : Assessment of charge correction schemes and identification of the negative carbon vacancy at the quasicubic site
- 2013
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 88:23, s. 235209-1-235209-13
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Tidskriftsartikel (refereegranskat)abstract
- The carbon vacancy (VC) has been suggested by different studies to be involved in the Z1/Z2 defect-a carrier lifetime killer in SiC. However, the correlation between the Z1/Z2 deep level with VC is not possible since only the negative carbon vacancy (V−C) at the hexagonal site, V−C(h), with unclear negative-U behaviors was identified by electron paramagnetic resonance (EPR). Using freestanding n-type 4H-SiC epilayers irradiated with low energy (250 keV) electrons at room temperature to introduce mainly VC and defects in the C sublattice, we observed the strong EPR signals of V−C(h) and another S = 1/2 center. Electron paramagnetic resonance experiments show a negative-U behavior of the two centers and their similar symmetry lowering from C3v to C1h at low temperatures. Comparing the 29Si and 13C ligand hyperfine constants observed by EPR and first principles calculations, the new center is identified as V−C(k). The negative-U behavior is further confirmed by large scale density functional theory supercell calculations using different charge correction schemes. The results support the identification of the lifetime limiting Z1/Z2 defect to be related to acceptor states of the carbon vacancy.
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| 5. |
- Yahiro, H., et al.
(författare)
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Copper-phthalocyanine encapsulated into zeolite-Y with high Si/Al : An EPR study
- 2005
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 415:1-3, s. 126-130
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Tidskriftsartikel (refereegranskat)abstract
- Copper (II) phthalocyanine (CuPc) molecules encapsulated into zeolite-Y with Si/Al ratios of 2.7 and 410 were prepared by an in situ synthesis and characterized by UV-Vis and electron paramagnetic resonance (EPR) spectroscopies. Resolved Cu-hyperfine and N-superhyperfine structures were observed in the EPR spectrum of CuPc encapsulated into zeolite-Y with a high Si/Al ratio. UV-Vis and EPR studies as well as theoretical calculations suggest that the encapsulated CuPc molecule was distorted in zeolite-Y with keeping of the square-planar symmetry around the center copper (II) ion. © 2005 Elsevier B.V. All rights reserved.
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| 6. |
- Tien Son, Nguyen, et al.
(författare)
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Negative-U System of Carbon Vacancy in 4H-SiC
- 2012
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 109:18, s. 187603-
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Tidskriftsartikel (refereegranskat)abstract
- Using electron paramagnetic resonance (EPR), energy levels of the carbon vacancy (V-C) in 4H-SiC and its negative-U properties have been determined. Combining EPR and deep-level transient spectroscopy we show that the two most common defects in as-grown 4H-SiC-the Z(1/2) lifetime-limiting defect and the EH7 deep defect-are related to the double acceptor (2 - vertical bar 0) and single donor (0 vertical bar +) levels of V-C, respectively.
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| 7. |
- Walsh, Roddy, et al.
(författare)
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Enhancing rare variant interpretation in inherited arrhythmias through quantitative analysis of consortium disease cohorts and population controls
- 2021
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Ingår i: Genetics in Medicine. - : Nature Publishing Group. - 1098-3600 .- 1530-0366. ; 23:1, s. 47-58
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Stringent variant interpretation guidelines can lead to high rates of variants of uncertain significance (VUS) for genetically heterogeneous disease like long QT syndrome (LQTS) and Brugada syndrome (BrS). Quantitative and disease-specific customization of American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines can address this false negative rate.Methods: We compared rare variant frequencies from 1847 LQTS (KCNQ1/KCNH2/SCN5A) and 3335 BrS (SCN5A) cases from the International LQTS/BrS Genetics Consortia to population-specific gnomAD data and developed disease-specific criteria for ACMG/AMP evidence classes-rarity (PM2/BS1 rules) and case enrichment of individual (PS4) and domain-specific (PM1) variants.Results: Rare SCN5A variant prevalence differed between European (20.8%) and Japanese (8.9%) BrS patients (p = 5.7 x 10(-18)) and diagnosis with spontaneous (28.7%) versus induced (15.8%) Brugada type 1 electrocardiogram (ECG) (p = 1.3 x 10(-13)). Ion channel transmembrane regions and specific N-terminus (KCNH2) and C-terminus (KCNQ1/KCNH2) domains were characterized by high enrichment of case variants and >95% probability of pathogenicity. Applying the customized rules, 17.4% of European BrS and 74.8% of European LQTS cases had (likely) pathogenic variants, compared with estimated diagnostic yields (case excess over gnomAD) of 19.2%/82.1%, reducing VUS prevalence to close to background rare variant frequency.Conclusion: Large case-control data sets enable quantitative implementation of ACMG/AMP guidelines and increased sensitivity for inherited arrhythmia genetic testing.
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| 10. |
- Zetterling, Carl-Mikael, et al.
(författare)
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SiC MISFETs with MBE-grown AlN gate dielectric
- 2000
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Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 338-342, s. 1315-1318
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Tidskriftsartikel (refereegranskat)abstract
- Metal-Insulator-Semiconductor Field Effect Transistors (MISFETs) with ion implanted source and drain junctions have been made in 6H silicon carbide (SiC). Aluminum nitride (AlN) was used as the insulating gate dielectric, and was grown using molecular beam epitaxy (MBE). Gate controlled transistor operation was shown with an inversion layer mobility of 10-20 cm2/Vs. However, due to relaxation of the AlN film, the gate leakage was excessive, which precluded a thorough investigation of the transistor characteristics. This paper describes the manufacturing process and current voltage characteristics, and an improved process sequence is also proposed.
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