| 1. |
- 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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| 2. |
- 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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| 3. |
- Gali, A., et al.
(författare)
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Ab initio supercell calculations on aluminum-related defects in SiC
- 2007
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:4
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio supercell calculations of the binding energies predict complex formation between aluminum and carbon interstitials in SiC. In high-energy implanted SiC aluminum acceptor can form very stable complexes with two carbon interstitials. We also show that carbon vacancy can be attached to shallow aluminum acceptor. All of these defects produce deep levels in the band gap. The possible relation of these defects to the recently found aluminum-related deep-level transient spectroscopy centers is discussed. © 2007 The American Physical Society.
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| 4. |
- Gali, A, et al.
(författare)
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Activation of shallow boron acceptor in CB coimplanted silicon carbide : A theoretical study
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:10, s. 102108-
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio supercell calculations have been carried out to investigate the complexes of boron acceptors with carbon self-interstitials in cubic silicon carbide. Based on the calculated binding energies, the complex formation of carbon interstitials with shallow boron acceptor and boron interstitial is energetically favored in silicon carbide. These bistable boron defects possess deep, negative- U occupation levels in the band gap. The theoretical results can explain the observed activation rates in carbon-boron coimplantation experiments. © 2005 American Institute of Physics.
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