| 1. |
- Khirunenko, L.I., et al.
(författare)
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Complexes of self-interstitials with oxygen atoms in germanium
- 2008
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 11:5, s. 344-347
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Tidskriftsartikel (refereegranskat)abstract
- Interactions of germanium self-interstitials with interstitial oxygen atoms in Ge crystals have been studied by combining experimental and theoretical methods. Self-interstitials were created in oxygen-rich Ge crystals by irradiation with MeV electrons at 80 K, and I-O-related complexes were studied by means of infrared absorption spectroscopy, while the density functional theory was used to model structures, local vibrational modes and electronic properties of IO and I2O centers. It is argued that two absorption lines at 674 and 602 cm-1, which develop upon annealing of irradiated Ge:O crystals in the temperature range 180-220 K, are related to IO complexes, while another set of bands at 713 and 803 cm-1 is related to I2O. Those assignments are supported by the comparison with the calculated local vibrational modes of the defects.
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| 2. |
- Markevich, V.P., et al.
(författare)
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Electronic properties of vacancy-oxygen complexes in SiGe alloys
- 2003
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 340, s. 790-4
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Tidskriftsartikel (refereegranskat)abstract
- Capacitance transient techniques, combined with ab initio modeling, were employed to study the electronic properties and structure of vacancy-oxygen (VO) complexes in unstrained Czochralski-grown Si1-xGex crystals (0
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| 3. |
- Markevich, V.P., et al.
(författare)
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Reconfigurations and diffusion of trivacancy in silicon
- 2012
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 107:15, s. 2974-2977
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Tidskriftsartikel (refereegranskat)abstract
- Disappearance of the divacancy (V2) and trivacancy (V3) complexes upon isochronal and isothermal annealing of electron irradiated Si:O crystals has been studied by means of deep level transient spectroscopy. The annealing studies have shown that the V2 and V3 defects are mobile in Si at T>200 °C and in oxygen-rich material are trapped by interstitial oxygen atoms so resulting in the appearance of V2O and V3O defects. The activation energies for diffusion of the V2 and V3 centers have been determined. Density functional modeling calculations have been carried out to investigate the migration and reorientation mechanisms of V3 in large silicon supercells. It is proposed that these comprise a sequence of transformations between V3(D3) and V3(C2v) configurations.
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| 4. |
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| 5. |
- Markevich, V.P., et al.
(författare)
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Tin-vacancy complex in germanium
- 2011
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 109, s. 083705-1
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Tidskriftsartikel (refereegranskat)abstract
- Electrically active defects introduced into Ge crystals co-doped with tin and phosphorus atoms by irradiation with 6 MeV electrons have been studied by means of transient capacitance techniques and ab-initio density functional modeling. It is shown that Sn atoms are effective traps for vacancies (V) in the irradiated Ge:Sn+P crystals. The electronic structure of Sn-V is unraveled on the basis of hybrid states from a Sn atom and a divacancy. Unlike the case for Si, Sn-V in Ge is not a donor. A hole trap with 0.19 eV activation energy for hole emission to the valence band is assigned to an acceptor level of the Sn-V complex. The Sn-V complex anneals out upon heat-treatments in the temperature range 50–100 °C. Its disappearance is accompanied by the formation of phosphorus-vacancy centers.
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| 6. |
- Murin, L.I., et al.
(författare)
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Isotopic effects on vibrational modes of thermal double donors in Si and Ge
- 2001
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Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 308-310, s. 290-293
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Tidskriftsartikel (refereegranskat)abstract
- The local vibrational modes of thermal double donors in Si and Ge are investigated by FTIR and ab initio modelling. At most, two oxygen modes are detected from each donor, which exhibit regular shifts with increasing donor number. By using mixtures of 16O and 18O, it is found that in Si the upper band does not yield any new modes suggesting that any oxygen atom is decoupled from any other. However, the lower frequency bands exhibit unique mixed modes proving for the first time that oxygen atoms are coupled together and in close spatial proximity. Ab initio calculations demonstrate that the modes and their isotopic shifts are consistent with a model involving two parallel chains of oxygen atoms linking second neighbour Si atoms, terminated by O-atoms close to the normal position for interstitial O. © 2001 Elsevier Science B.V. All rights reserved.
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| 7. |
- Litvinov, V V, et al.
(författare)
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Calibration factor for determination of interstitial oxygen concentration in germanium by infrared absorption
- 2005
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Ingår i: Solid State Phenomena. - 1012-0394. ; 108-109, s. 735-740
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Tidskriftsartikel (refereegranskat)abstract
- Intensities of infrared absorption due to asymmetric stretching vibrations of interstitial oxygen atoms in Ge crystals enriched with O-16 and O-18 isotopes have been compared with oxygen concentrations determined by means of secondary ion mass spectrometry (SIMS). For Ge samples with oxygen content less than 510(17) cm(-3) a good correlation has been found between the values of oxygen concentration and values of absorption coefficient in maximum of the absorption band at 855.6 cm(-1) with a proportionality coefficient C-O = 0.95 10(17) cm(-2). It is argued that kinetics of oxygen-related thermal double donor formation and oxygen loss upon heat-treatments of Ge crystals at 350 degrees C cannot be described properly with the application of calibration coefficient C-O 510(16) cm(-2), which is widely used for the determination of oxygen concentration in Ge crystals.
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| 8. |
- Litvinov, V. V., et al.
(författare)
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Determination of interstitial oxygen concentration in germanium by infrared absorption
- 2006
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Ingår i: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 100:3
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Tidskriftsartikel (refereegranskat)abstract
- The intensities of infrared absorption due to the asymmetric stretching vibrations of interstitial oxygen atoms in Ge crystals enriched with O-16 and O-18 isotopes have been compared with oxygen concentrations determined by means of secondary ion mass spectrometry. For Ge samples with oxygen content less than 5 x 10(17) cm(-3), a good correlation has been found between the values of oxygen concentration and the values of the absorption coefficient at the maximum of the O-16(i) related absorption band at 855.6 cm(-1) with a proportionality coefficient C-O = 1.05 x 10(17) cm(-2). (c) 2006 American Institute of Physics.
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| 9. |
- Litvinov, V V, et al.
(författare)
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Oxygen loss and thermal double donor formation in germanium
- 2006
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001. ; 9:4-5, s. 619-624
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Tidskriftsartikel (refereegranskat)abstract
- Kinetics of interstitial oxygen loss and oxygen-related thermal double donor (TDD) generation upon heat treatments of Ge:O crystals at 350 degrees C have been studied. The TDD concentration (N-TDD) was derived from Hall effect measurements in the temperature range 77-400 K. The bistability of the first TDD species was taken into account. The interstitial oxygen concentration ([O-i]) in the crystals was determined from measurements of the intensity of the infrared absorption band at 855 cm(-1) at room temperature with the use of a recently obtained calibration coefficient Co = 1.05 x 10(17) cm(-2). From an analysis of the [O-i](t) and N-TDD(t) kinetics a confirmation of recent suggestions about faster diffusivity of small oxygen clusters compared to the diffusivity of single interstitial oxygen atoms was obtained. Average numbers (N) of oxygen atoms lost per TDD species created, N = Delta[O-i]/N-TDD, were calculated at different stages of the TDD generation. The obtained values of N are consistent with those expected in accordance with the recent models of the TDD structure. In particular, an average number of oxygen atoms per TDD species was about 5 at initial stages of the heat treatment when the first members (the TDD2 and TDD3 species) of the TDD family were dominant. N was found to be about 10 after extended anneals at 350 degrees C when the TDD6 and TDD7 species were dominant.
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| 10. |
- Carvalho, A., et al.
(författare)
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Oxygen defects in irradiated germanium
- 2007
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Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 18:7, s. 781-786
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Tidskriftsartikel (refereegranskat)abstract
- The defects present in oxygen-rich irradiated germanium have been extensively characterised from an experimental point of view. Here, we summarise recent theoretical findings obtained using the cluster method and discuss their relation with the experimental data. In order to find a microscopic interpretation of the reactions taking place in this material upon annealing up to 400°C, we performed nudged elastic band (NEB) calculations of the migration and dissociation paths of VO, as well as a modelling of other oxygen-related complexes that are expected to form in this temperature range. Energy barriers of 1.5 (1.1) eV and 1.2 (0.9) eV for the dissociation and migration of the neutral (negatively charged) VO defect are found. We compare these with the activation energies estimated from the analysis of Hall effect, deep level transient spectroscopy (DLTS) and infra-red (IR) spectroscopy annealing data reported in literature.
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