| 1. |
- Hoffmann, L., et al.
(författare)
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Weakly bound carbon-hydrogen complex in silicon
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 61:24, s. 16659-16666
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Tidskriftsartikel (refereegranskat)abstract
- Local vibrational modes of a weakly bound carbon-hydrogen complex in silicon have been identified with infrared-absorption spectroscopy. After implantation of protons at ∼20 K and subsequent annealing at 180 K, two carbon modes at 596 and 661 cm-1, and one hydrogen mode at 1885 cm-1 are observed. The three modes originate from the same complex, which is identified as bond-centered hydrogen in the vicinity of a nearby substitutional carbon atom. Ab initio theory has been applied to calculate the structure and local modes of carbon-hydrogen complexes with hydrogen located at the first, second, and third nearest bond-center site to substitutional carbon. The results support our assignment.
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| 2. |
- Lavrov, E.V., et al.
(författare)
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Combined infrared absorption and modeling study of a dicarbon-dihydrogen defect in silicon
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 62:19, s. 12859-12867
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Tidskriftsartikel (refereegranskat)abstract
- Crystalline silicon samples doped with carbon were irradiated with electrons and subsequently implanted with protons. Infrared-absorption measurements revealed local modes of hydrogen and carbon at 2967.4, 911.7, and 654.7 cm-1, which originate from the same defect. Measurements on samples codoped with different carbon and hydrogen isotopes showed that the defect contains two equivalent carbon and two equivalent hydrogen atoms. From uniaxial stress measurements, the defect is found to display trigonal symmetry. Ab initio local-density-functional theory was applied to calculate the structure and local vibrational modes of defects with pairs of equivalent carbon and hydrogen atoms. Based on these results, the observed local modes are ascribed to a defect with two adjacent substitutional carbon atoms, each of which binds a hydrogen atom located between the carbon atoms.
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| 3. |
- Lavrov, E. V., et al.
(författare)
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Local vibrational modes of two neighboring substitutional carbon atoms in silicon
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 62:1, s. 158-165
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Tidskriftsartikel (refereegranskat)abstract
- Infrared absorption measurements on n-type silicon doped with carbon and irradiated with electrons at room temperature have revealed new absorption lines at 527.4 and 748.7 cm-1, which originate from the same defect. The 748.7-cm-1 line is observed only when the sample is cooled in the dark and the spectrum is measured through a low-pass filter with cutoff frequency below 6000 cm-1. Light with frequency above 6000 cm-1 removes this line and generates the 527.4-cm-1 line. Comparison with spectra recorded on irradiated silicon doped with 13C shows that the two lines represent local vibrational modes of carbon. The annealing behavior of the 748.7-cm-1 line is identical to that of the EPR signal originating from the negative charge state of two adjacent substitutional carbon atoms (Cs-Cs)-. The 527.4- and 748.7-cm-1 lines are ascribed to the E modes of Cs-Cs in the neutral and negative charge states, respectively. The structure and local vibrational modes of (Cs-Cs)0 and (Cs-Cs)- have been calculated by ab initio local density functional theory. The calculated structures agree qualitatively with those obtained previously by Hartree-Fock methods, but the calculated Si-C and C-C bond lengths differ somewhat. The calculated local mode frequencies are in good agreement with those observed. The formation of Cs-Cs has also been investigated. It is suggested that the center is formed when a vacancy is trapped by the metastable substitutional carbon-interstitial carbon center, Cs-Ci.
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