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| 2. |
- Nguyen, Son Tien, 1953-, et al.
(författare)
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Defects introduced by electron-irradiation at low temperatures in SiC
- 2009
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Ingår i: Materials Science Forum Vols. 615-617. - : Trans Tech Publicarions. - 9780878493340 ; , s. 377-380
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Konferensbidrag (refereegranskat)abstract
- Defects introduced by electron irradiation at ~80-100 K in 3C-, 4H- and 6H-SiC were studied by electron paramagnetic resonance (EPR). A number of EPR spectra, labelled LE1-10, were detected. Combining EPR and supercell calculations, we will show that the LE1 center in 3C-SiC with C2v symmetry and an electron spin S=3/2 is related to the (VSi-Sii)3+ Frenkel pair between the silicon vacancy and a second neighbour Sii interstitial along the <100> direction. Results on other centers, possibly also related to interstitials, are discussed.
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| 3. |
- Nguyen, Son Tien, et al.
(författare)
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Identification of a Frenkel-pair defect in electron-irradiated 3C SiC
- 2009
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 80, s. 125201-
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Tidskriftsartikel (refereegranskat)abstract
- Anelectron paramagnetic resonance (EPR) spectrum labeled LE1 was observed inn-type 3C SiC after electron irradiation at low temperatures (~80–100 K).A hyperfine interaction with four nearest C neighbors similar tothat of the well-known silicon vacancy in the negative chargestate was observed, but the LE1 center has a lowersymmetry, C2v. Supercell calculations of different configurations of silicon vacancy-interstitialFrenkel-pairs, VSi-Sii, were performed showing that pairs with a nearestneighbor Si interstitial are unstable—VSi and Sii will automatically recombine—whereaspairs with a second neighbor Sii are stable. Comparing thedata obtained from EPR and supercell calculations, the LE1 centeris assigned to the Frenkel-pair between VSi and a secondneighbor Sii interstitial along the [100] direction in the 3+charge state, V-Si. In addition, a path for the migrationof Si was found in 3C SiC. In samples irradiatedat low temperatures, the LE1 Frenkel-pair was found to bethe dominating defect whereas EPR signals of single vacancies werenot detected. The center disappears after warming up the samplesto room temperature.
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| 4. |
- Nguyen, Tien Son, et al.
(författare)
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Identification of divacancies in 4H-SiC
- 2006
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Ingår i: Physica B: Condensed Matter, Vols. 376-377. - : Elsevier BV. ; , s. 334-337
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Konferensbidrag (refereegranskat)abstract
- The P6/P7 centers in 4H-SiC were studied by electron paramagnetic resonance (EPR) and ab initio supercell calculations. The hyperfine coupling constants of C and Si neighbors obtained by EPR are in good agreement with the calculated values for the neutral divacancy, VCVsi0. Our results suggest that the P6/P7 centers, which were previously assigned to the photo-excited triplet states of the carbon vacancy-carbon antisite pairs in the double positive charge state (VCCsi2+), are related to the triplet ground states of the C-3v/C-1h si configurations of VCVsi0 (c) 2006 Elsevier B.V. All rights reserved.
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