| 1. |
- Nylandsted Larsen, A., et al.
(författare)
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Tin-vacancy acceptor levels in electron-irradiated n-type silicon
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 62:7, s. 4535-4544
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Tidskriftsartikel (refereegranskat)abstract
- Si crystals (n-type, fz) with doping levels between 1.5×1014 and 2×1016 cm-3 containing in addition ∼1018 Sn/cm3 were irradiated with 2-MeV electrons to different doses and subsequently studied by deep level transient spectroscopy, Mössbauer spectroscopy, and positron annihilation. Two tin-vacancy (Sn-V) levels at Ec-0.214 eV and Ec-0.501 eV have been identified (Ec denotes the conduction band edge). Based on investigations of the temperature dependence of the electron-capture cross sections, the electric-field dependence of the electron emissivity, the anneal temperature, and the defect-introduction rate, it is concluded that these levels are the double and single acceptor levels, respectively, of the Sn-V pair. These conclusions are in agreement with electronic structure calculations carried out using a local spin-density functional theory, incorporating pseudopotentials to eliminate the core electrons, and applied to large H-terminated clusters. Thus, the Sn-V pair in Si has five different charge states corresponding to four levels in the band gap.
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| 2. |
- Doyle, J. P., et al.
(författare)
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Characterization of deep level defects in 4H and 6H SiC via DLTS, SIMS and MeV e-beam irradiation
- 1996
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Ingår i: III-nitride, SiC and diamond materials for electronic devices. ; , s. 519-524
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Konferensbidrag (refereegranskat)abstract
- Electrically active defects in both 4H and 6H polytypes of SiC have been observed through the use of deep level transient spectroscopy (DLTS). Schottky contacts were grown by VPE with doping concentrations, the epitaxial layer having a doping concentration in the range of 10 exp 14/cu cm to 10 exp 17/cu cm. Numerous levels have been found in the as-grown n-type 6H-SiC samples, and SIMS and MeV electron irradiation have been employed to correlate the defect levels to impurities or structural defects. In contrast, only a single level is observed in the as-grown 4H-SiC samples.
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| 3. |
- Doyle, J. P., et al.
(författare)
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Electrically active point defects in n-type 4H–SiC
- 1998
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 84:3, s. 61-68
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Tidskriftsartikel (refereegranskat)abstract
- An electrically active defect has been observed at a level position of ∼ 0.70 eV below the conduction band edge (Ec) with an extrapolated capture cross section of ∼ 5×10−14 cm2 in epitaxial layers of 4H–SiC grown by vapor phase epitaxy with a concentration of approximately 1×1013 cm−3. Secondary ion mass spectrometry revealed no evidence of the transition metals Ti, V, and Cr. Furthermore, after electron irradiation with 2 MeV electrons, the 0.70 eV level is not observed to increase in concentration although three new levels are observed at approximately 0.32, 0.62, and 0.68 eV below Ec with extrapolated capture cross sections of 4×10−14, 4×10−14, and 5×10−15 cm2, respectively. However, the defects causing these levels are unstable and decay after a period of time at room temperature, resulting in the formation of the 0.70 eV level. Our results suggest strongly that the 0.70 eV level originates from a defect of intrinsic nature. The unstable behavior of the electron irradiation-induced defects at room temperature has not been observed in the 6H–SiC polytype.
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| 4. |
- Doyle, J P, et al.
(författare)
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Observation of near-surface electrically active defects in n-type 6H-SiC
- 1998
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 83, s. 3649-3651
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Tidskriftsartikel (refereegranskat)abstract
- In n-type 6H-SiC epitaxial layers grown by vapor phase epitaxy, we find that in contrast to the majority of the epitaxial layer, where electrically active defects are observed with a concentration less than 1 X 10(-13) cm(-3), a region near the front surface contains defects with concentrations approaching 10(14) cm(-3). A relationship between the near-surface defects and metallic impurities is suggested by a Ti concentration of 1 X 10(16) cm(-3) in this region. The high concentration of near surface defects is found to significantly reduce the carrier lifetime. (C) 1998 American Institute of Physics. [S0021-8979(98)03007-2].
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| 5. |
- Hermansson, J., et al.
(författare)
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Complexes of the self-interstitial with oxygen in irradiated silicon : A new assignment of the 936 cm-1 band
- 2001
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 302-303, s. 188-192
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Three vibrational infrared absorption bands at about 936, 944 and 956 cm-1 appear commonly in spectra of Czochralski-grown silicon irradiated at low temperatures. All three bands have earlier been assigned to local vibrational modes related to oxygen in the complex of the silicon and the oxygen interstitials (IOi). However, it is shown that such an assignment of the 936 cm-1 band clearly is inconsistent with many facts and observations and that the band is most likely due to oxygen vibrations in the Si interstitial pair and interstitial oxygen complex, I2Oi. © 2001 Published by Elsevier Science B.V.
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| 6. |
- Kuznetsov, A.Yu., et al.
(författare)
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Diffusion of phosphorus in strained Si/SiGe/Si heterostructures
- 1999
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Ingår i: Materials Research Society Symposium - Proceedings. - San Francisco, CA, USA. ; 568:Warrendale, PA, United States, s. 271-276
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorus diffusion in a biaxially compressed Si0.87Ge0.13 film has been investigated in the temperature range of 810-900 °C. A significant enhancement of the P diffusion in the biaxially compressed Si0.87Ge0.13 in comparison with P diffusion in Si is observed. Injection of Si self-interstitials (I) during oxidation of a Si-cap in Si/Si0.87Ge0.13/Si heterostructures is used to characterize the atomic mechanism of P diffusion in Si0.87Ge0.13. It is found that the upper limit of the interstitial fraction of the P diffusion in Si0.87Ge0.13 is 0.87 of that in Si. A comparison between B and P diffusivities in SiGe supports the hypothesis of the pairing-controlled mechanism for the diffusion of B in SiGe.
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| 7. |
- Lindstrom, J.L., et al.
(författare)
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Defect engineering in Czochralski silicon by electron irradiation at different temperatures
- 2002
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 186:1-4, s. 121-125
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Tidskriftsartikel (refereegranskat)abstract
- Infrared absorption studies of defect formation in Czochralski silicon irradiated with fast electrons in a wide range of temperatures (80-900 K) have been performed. The samples with different contents of oxygen (16O,18O) and carbon (12C,13C) isotopes were investigated. The main defect reactions are found to depend strongly on irradiation temperature and dose, as well as on impurity content and pre-history of the samples. Some new radiation-induced defects are revealed after irradiation at elevated temperatures as well as after a two-step (hot+room-temperature (RT)) irradiation. © 2002 Elsevier Science B.V. All rights reserved.
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| 8. |
- Lindstrom, J.L., et al.
(författare)
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Interaction between self-interstitials and the oxygen dimer in silicon
- 2001
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 308-310, s. 284-289
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Tidskriftsartikel (refereegranskat)abstract
- Interactions between the oxygen dimer (O2i) and silicon self-interstitials (I) and vacancies (V) have been studied in Czochralski-grown silicon (Cz-Si) crystals using infrared absorption and deep level transient spectroscopies. The focus in this report is on reactions of O2i with I. The first step in this interaction is found to be the formation of a self-interstitial-dioxygen centre (IO2i) with oxygen-related local vibrational mode (LVM) bands at 922 and 1037 cm-1. During the second formation step, another centre, I2O2i, with LVM bands at 918 and 1034 cm-1 is suggested to appear. A Si-related band at about 545 cm-1 is also assigned to both the IO2i and I2O2i centres. The IO2i centre is found to be electrically active with an acceptor level at Ec - 0.11 eV. The both defects, IO2i and I2O2i, are stable at room temperature and anneal out at about 400 and 550 K, respectively. © 2001 Elsevier Science B.V. All rights reserved.
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| 9. |
- Slotte, J., et al.
(författare)
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Fluence, flux, and implantation temperature dependence of ion-implantation-induced defect production in 4H-SiC
- 2005
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 97:3
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Tidskriftsartikel (refereegranskat)abstract
- Vacancy-type defect production in Al- and Si-implanted 4H-SiC has been studied as a function of ion fluence, ion flux, and implantation temperature in the projected ion range region by positron annihilation spectroscopy and Rutherford backscattering techniques. Ion channeling measurements show that the concentration of displaced silicon atoms increases rapidly with increasing ion fluence. In the ion fluence interval of 10(13)-10(14) cm(-2) the positron annihilation parameters are roughly constant at a defect level tentatively associated with the divacancy VCVSi. Above the ion fluence of 10(14) cm(-2) larger vacancy clusters are formed. For implantations as a function of ion flux (cm(-2) s(-1)), ion channeling and positron annihilation measurements behave similarly, i.e., indicating increasing damage in the projected range region with increasing ion flux. However, for samples implanted at different temperatures the positron annihilation parameter S shows a clear minimum at approximately 100 degreesC, whereas the normalized backscattering yield decrease continuously with increasing implantation temperature. This is explained by the formation of larger vacancy clusters when the implantation temperature is increased.
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| 10. |
- Svensson, B.G., et al.
(författare)
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Ion implantation processing and related effects in SiC
- 2006
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Ingår i: Silicon Carbide and Related Materials 2005, Pts 1 and 2. - 9780878494255 ; , s. 781-786
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Konferensbidrag (refereegranskat)abstract
- A brief survey is given of some recent progress regarding ion implantation processing and related effects in 4H- and 6H-SiC. Four topics are discussed; an empirical ion range distribution simulator, dynamic defect annealing during implantation, formation of highly p(+)-doped layers, and deactivation of N donors by ion-induced defects.
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