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  • 1.
    Andersen, O.
    et al.
    Centre for Electronic Materials, University of Manchester.
    Dobaczewski, L.
    Centre for Electronic Materials, University of Manchester.
    Peaker, A.R.
    Centre for Electronic Materials, University of Manchester.
    Nielsen, K. Bonde
    Institute of Physics and Astronomy, University of Aarhus.
    Hourahine, B.
    Department of Physics, University of Exeter.
    Jones, R.
    Department of Physics, University of Exeter.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Piezospectroscopic analysis of the hydrogen-carbon complexes in silicon2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, p. 139-142Article in journal (Refereed)
    Abstract [en]

    We have observed the donor (Ec-0.22 eV) and acceptor (Ec-0.16 eV) levels related to hydrogen-carbon complexes in silicon. The donor level is only detected at low temperatures after proton implantation. This hydrogen-carbon complex irreversibly reconfigures at temperatures above 225 K to a configuration characterized by the acceptor level, which is stable up to room temperature. The same acceptor level is also observed after atomic hydrogen diffusion. We have used Laplace transform deep level transient spectroscopy (DLTS) to show the influence of uniaxial stress on the electron emission process and the effect of the stress-induced alignment for the acceptor state. The pattern of the Laplace DLTS peak splittings indicate a trigonal symmetry of the defect. First principles calculations were carried out on the hydrogen-carbon defects with a view of determining their electrical levels and stress response for comparison with the experimental results.

  • 2.
    Blumenau, A.T.
    et al.
    Department of Physics, Universität Paderborn.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Frauenheim, T.
    Department of Physics, Universität Paderborn.
    Basal plane partial dislocations in silicon carbide2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 160-164Article in journal (Refereed)
    Abstract [en]

    Under operating conditions (forward bias) bipolar 4H- and 6H-SiC devices are known to degrade rapidly through stacking fault formation and expansion in the basal plane. It has been suggested that a recombination-enhanced dislocation glide (REDG) mechanism allows the bordering Shockley partial dislocations to overcome their barrier to glide motion and thus results in the observed stacking fault growth. In this work, we investigate the structure and properties of the participating Shockley partials by means of density functional-based atomistic calculations. Their glide motion is modelled in a process involving the formation and subsequent migration of kinks. This in combination with an analysis of the electronic structure of the partials allows an identification of those types which will be affected by the REDG mechanism.

  • 3.
    Carvalho, A.
    et al.
    School of Physics, University of Exeter.
    Barker, S.J.
    Centre for Electronic Materials and Devices, Imperial College, London.
    Jones, R.
    School of Physics, University of Exeter.
    Williams, R.S.
    Centre for Electronic Materials and Devices, Imperial College, London.
    Ashwin, M.J.
    Centre for Electronic Materials and Devices, Imperial College, London.
    Newman, R.C.
    Centre for Electronic Materials and Devices, Imperial College, London.
    Stavrinou, P.N.
    Centre for Electronic Materials and Devices, Imperial College, London.
    Parry, G.
    Centre for Electronic Materials and Devices, Imperial College, London.
    Jones, T.S.
    Centre for Electronic Materials and Devices, Imperial College, London.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Identification of the local vibrational modes of small nitrogen clusters in dilute GaAsN2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 401-402, p. 339-342Article in journal (Refereed)
    Abstract [en]

    Ultra-high-resolution infra-red local vibrational mode (IR LVM) spectroscopy measurements together with density-functional calculations have been used to identify the signatures of close substitutional nitrogen (NAs) pairs in GaAs1 - x Nx alloys with concentrations of x < 0.025. We show that the presence of sub-peaks close to the NAs absorption band can be attributed to nitrogen pairs up to fourth neighbor position. Additionally, we suggest that the nitrogen pairs which give rise to the deepest levels below the conduction band edge are the first to be removed upon annealing

  • 4.
    Carvalho, A.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Goss, J.
    School of Natural Science, University of Newcastle upon Tyne.
    Janke, C.
    School of Physics, University of Exeter.
    Coutinho, J.
    Department of Physics, University of Aveiro.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Self-interstitials and Frenkel pairs in electron-irradiated germanium2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 401-402, p. 495-498Article in journal (Refereed)
    Abstract [en]

    First principles calculations were used to study the structures and electrical levels of the self-interstitial in Ge. We considered the possibility of structural changes consequent with change in charge state and show these have important implications in the mobility and electrical activity of the defect. The theoretical model is compared to the results of low temperature electron irradiation in germanium reported in the literature.

  • 5.
    Carvalho, A.
    et al.
    Swiss Federal Institute of Technology.
    Tagantsev, A.
    Swiss Federal Institute of Technology.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    University of Newcastle Upon Tyne.
    Setter, N.
    Swiss Federal Institute of Technology.
    Intrinsic defects in CdTe and CdZnTe alloys2009In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 404, no 23-24, p. 5019-5021Article in journal (Refereed)
    Abstract [en]

    The Cd vacancy (VCd) and Te anti-site (TeCd) are two dominant defects in CdTe and CdZnTe alloys grown in Terich conditions. We examine the properties of these two intrinsic defects in Cd1-xZnxTe alloys with x < 0:5 using first-principles calculations. It is shown that Cd vacancies become progressively more favourable with increasing Zn content, in contrast with Te anti-sites, which show the opposite behaviour, explaining the trend towards p-type conductivity in Cd1-xZnxTe.

  • 6.
    Coomer, B.J.
    et al.
    School of Physics, University of Exeter.
    Goss, J.P.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Interstitial aggregates and a new model for the I1/W optical centre in silicon1999In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 273-274, p. 505-508Article in journal (Refereed)
    Abstract [en]

    The properties of di-interstitial (I2), tri-interstitial (I3) and tetra-interstitial (I4) structures in silicon were studied by employing first principles local-density-functional (LDF) theory. A tri-interstitial defect can account for many of the fundamental properties of the I1/W-optical center which is observed in irradiated, annealed silicon. Energy comparisons between di-interstitial defects reveal four low-energy structures within 0.5 eV of each other.

  • 7.
    Coomer, B.J.
    et al.
    School of Physics, University of Exeter.
    Resende, A.
    School of Physics, University of Exeter.
    Goss, J.P.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    The divacancy in silicon and diamond1999In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 273-274, p. 520-523Article in journal (Refereed)
    Abstract [en]

    First-principles studies of the divacancy (V2) in both silicon and diamond are reported. We demonstrate that the contrasting experimental spin-density localisation of both systems can be explained through the one-electron pictures arising from opposing distortions

  • 8.
    Coutinho, J.
    et al.
    Department of Physics, I3N, University of Aveiro, Campus Santiago.
    Janke, C.
    School of Physics, University of Exeter.
    Carvalho, A.
    School of Physics, University of Exeter.
    Torres, V.J.B.
    Department of Physics, I3N, University of Aveiro, Campus Santiago.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Jones, R.
    School of Physics, University of Exeter.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Strong compensation of n-type Ge via formation of donor-vacancy complexes2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 401-402, p. 179-183Article in journal (Refereed)
    Abstract [en]

    Vacancies and interstitials in semiconductors play a fundamental role in both high-temperature diffusion and low-temperature radiation and implantation damage. In Ge, a serious contender material for high-speed electronics applications, vacancies have historically been believed to dominate most diffusion related phenomena such as self-diffusivity or impurity migration. This is to be contrasted with silicon, where self-interstitials also play decisive roles, despite the similarities in the chemical nature of both materials. We report on density functional calculations of the formation and properties of vacancy-donor complexes in germanium. We predict that most vacancy-donor aggregates are deep acceptors, and together with their high solubilities, we conclude that they strongly contribute for inhibiting donor activation levels in germanium

  • 9.
    Coutinho, J.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Murin, L.I.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Markevich, V.P.
    Centre for Electronic Materials, University of Manchester.
    Lindström, J.L.
    Department of Physics, University of Lund.
    Over-coordinated oxygen in the interstitial carbon-oxygen complex2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, p. 305-308Article in journal (Refereed)
    Abstract [en]

    The interstitial carbon-oxygen complex is one of the most prominent defects formed in e-irradiated Cz-Si containing carbon. Stress alignment investigations have shown that the oxygen atom only perturbs the carbon interstitial but the lack of a high frequency oxygen mode has been taken to imply that the oxygen atom is over-coordinated. Local vibrational mode spectroscopy and ab initio modeling are used to investigate the defect. We find new modes whose oxygen isotopic shifts, along with the piezoscopic stress-energy tensor support the trivalent model, thus providing evidence for oxygen over-coordination.

  • 10.
    Coutinho, J.
    et al.
    Department of Physics, University of Aveiro.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    The formation, dissociation and electrical activity of divacancy-oxygen complexes in Si2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 523-527Article in journal (Refereed)
    Abstract [en]

    Density functional calculations are carried out on divacancy-oxygen (V2O and V2O2) complexes in silicon, paying particular attention to their formation and dissociation mechanisms as well as their electrical activity. The formation of V2O around 220°C is controlled by the diffusion of V2 to immobile oxygen traps, while it dissociates around 300°C into VO and V. V2O and V2O2 are found to possess deep single and double acceptor levels as well as deep donor levels similar to those of V2.

  • 11.
    Eberlein, T.A.G.
    et al.
    School of Physics, University of Exeter.
    Pinho, N.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Coomer, B.J.
    School of Physics, University of Exeter.
    Goss, J.P.
    School of Physics, University of Exeter.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Self-interstitial clusters in silicon2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308-310, p. 454-457Article in journal (Refereed)
    Abstract [en]

    Although there have been made many calculations for structures of the self-interstitial in Si and small aggregates of interstitials, In, there have been relatively few attempts to relate these defects with experimental data. Here, we discuss the assignments of the self-interstitial to the AA12 EPR centre and the di-interstitial to the P6 EPR centre.

  • 12.
    Fujita, N.
    et al.
    University of Exeter.
    Jones, R.
    University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    First-principles study on the local vibrational modes of nitrogen-oxygen defects in silicon2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 401-402, p. 159-162Article in journal (Refereed)
    Abstract [en]

    In this paper we investigate the interaction of nitrogen and oxygen by means of local density functional theory. While nitrogen-pair-oxygen defects N2-Om have been studied in detail previously, the existence and role of nitrogen-oxygen defects containing only one nitrogen atom (N- On) is still controversial. Motivated by recent infrared absorption measurements, where several new absorption lines were observed, we present first-principles studies on the ground state configuration, binding energy and local vibrational modes of NO and NO2. We suggest that the NO2 defect gives rise to the experimentally observed lines at 1002, 973 and 855 cm-1

  • 13.
    Hourahine, B.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Safonov, A.N.
    Department of Physics, University of Durham.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Estreicher, S.K.
    Department of Physics, Texas Tech University, Lubbock.
    Optically active hydrogen dimers in silicon1999In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 273-274, p. 176-179Article in journal (Refereed)
    Abstract [en]

    First-principles calculations are used to explore the structure and properties of several defects which are prominent luminescent centers in Si. The trigonal defects B41 and B711, which are known to contain two hydrogen atoms in equivalent and inequivalent sites, respectively, are attributed to a hexavacancy containing two H atoms in different configurations. It is suggested that the J luminescence centers arises from a stable hexavacancy without hydrogen atoms

  • 14.
    Hourahine, B.
    et al.
    Theoretische Physik, Universität Paderborn.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Frauenheim, T.
    Theoretische Physik, Universität Paderborn.
    Platinum and gold dihydrides in silicon2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 668-72Article in journal (Refereed)
    Abstract [en]

    The structural, electronic and vibrational properties of single substitutional platinum or gold atoms complexed with two hydrogen atoms in silicon are considered on the basis of local density functional theory. The calculated behaviour of these centres is compared with experimental results from infrared absorption and deep-level transient spectroscopy. In contrast with suggestions in the literature, based on hyperfine parameters of electron-paramagnetic resonance, we suggest that such complexes possess direct metal-H bonding.

  • 15.
    Hourahine, B.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Markevich, V.P.
    Centre for Electronic Materials, University of Manchester.
    Newman, R.C.
    Blacket Laboratory, Department of Physics, Imperial College, London.
    Hermansson, J.
    Department of Physics, University of Lund.
    Kleverman, M.
    Department of Physics, University of Lund.
    Lindström, J.L.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Murin, L.I.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Fukata, N.
    Institute of Materials Research, Tohoku University, Sendai.
    Suezawa, M.
    Institute of Materials Research, Tohoku University, Sendai.
    Evidence for H2* trapped by carbon impurities in silicon2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, p. 197-201Article in journal (Refereed)
    Abstract [en]

    Local mode spectroscopy and ab initio modelling are used to investigate two trigonal defects found in carbon-rich Si into which H had been in-diffused. Isotopic shifts with D and 13C are reported along with the effect of uniaxial stress. Ab initio modelling studies suggest that the two defects are two forms of the CH2* complex where one of the two hydrogen atoms lies at an anti-bonding site attached to C or Si, respectively. The two structures are nearly degenerate and possess vibrational modes in good agreement with those observed.

  • 16.
    Iwata, H.P.
    et al.
    Department of Physics and Measurement Technology, Linköping University.
    Lindefelt, U.
    Department of Physics and Measurement Technology, Linköping University.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Stacking faults in silicon carbide2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 165-70Article in journal (Refereed)
    Abstract [en]

    We review of our theoretical work on various stacking faults in SiC polytypes. Since the discovery of the electronic degradation phenomenon in 4H-SiC p-i-n diodes, stacking faults in SiC have become a subject of intensive study around the globe. At the beginning of our research project, the aim was to find the culprit for the degradation phenomenon, but in the course of this work we uncovered a wealth of information for the general properties of stacking faults in SiC. An intuitive perspective to the diverse nature of stacking faults in SiC will be given in this conference report.

  • 17.
    Jones, R.
    et al.
    School of Physics, University of Exeter.
    Coutinho, J.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Thermal double donors in Si and Ge2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, p. 8-12Article in journal (Refereed)
    Abstract [en]

    Three experiments appear to cast doubt on self-interstitial-free models of the family of thermal donors, based on oxygen defects of increasing size. These are (a) the rapid transformation of TDD(N) into TDD(N+1) with activation energies considerably lower than that of oxygen diffusion, (b) the lack of any appreciable spin-density on oxygen in TDD(N)+, and (c) the observation of only two oxygen related vibrational modes associated with each donor. However, we show that the oxygen-only model of the donors is compatible with experiment for a structure involving an insulating core with normal oxygen coordination, surrounded by over-coordinated oxygen atoms which are responsible for the donor activity. It is also shown that the calculated stress-energy tensors for the early donors are in good agreement with the measurements.

  • 18.
    Markevich, V.P.
    et al.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Murin, L.I.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Suezawa, M.
    Institute for Materials Research, Tohoku University.
    Lindström, J.C.
    Department of Physics, University of Lund.
    Coutinho, J.
    Department of Physics, University of Exeter.
    Jones, R.
    Department of Physics, University of Exeter.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Local vibrational mode bands of V-O-H complexes in silicon1999In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 273-274, p. 300-304Article in journal (Refereed)
    Abstract [en]

    H2 molecules, which are introduced into moderately doped silicon crystals by high-temperature in-diffusion from H2 gas ambient followed by fast cooling to room temperature, are found to interact effectively with the defects induced by irradiation of the crystals with fast electrons. In Czochralski-grown silicon crystals, the interaction of the mobile H2 molecules with vacancy-oxygen defects (A centers) leads to the creation of V-O-H2 complexes. This complex gives rise to infrared (IR) absorption lines at 943.5, 2126.4, and 2151.5 cm-1. Ab initio calculations showed that the most stable configuration of V-O-H2 consists of one oxygen and two hydrogen atoms sharing a vacancy site. It is suggested that the interaction of the V-O-H2 complexes with interstitial oxygen atoms results in the formation of V-O2-H2 complexes, which are responsible for the IR absorption line at 891.5 cm-1.

  • 19.
    Markevich, V.P.
    et al.
    University of Manchester.
    Peaker, A.R.
    University of Manchester.
    Hamilton, B.
    University of Manchester.
    Lastovskii, S.B.
    Scientific-Practical Materials Research Center of NAS of Belarus.
    Murin, L.Il
    Scientific-Practical Materials Research Center of NAS of Belarus.
    Coutinho, J.
    Department of Physics, University of Aveiro.
    Markevich, A.V.
    Department of Physics, University of Aveiro.
    Rayson, Mark
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Electrical, Electronic and Computer Engineering, University of Newcastle upon Tyne.
    Svensson, B.G.
    Department of Physics, Oslo University.
    Reconfigurations and diffusion of trivacancy in silicon2012In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 107, no 15, p. 2974-2977Article in journal (Refereed)
    Abstract [en]

    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.

  • 20.
    Markevich, V.P.
    et al.
    Centre for Electronic Materials, University of Manchester.
    Peaker, A.R.
    Centre for Electronic Materials, University of Manchester.
    Murin, L.I.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Coutinho, J.
    Department of Physics, University of Aveiro.
    Torres, V.J.B.
    Department of Physics, University of Aveiro.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Auret, F.D.
    Centre for Electronic Materials, University of Manchester.
    Abrosimov, N.V.
    Institute of Crystal Growth, Berlin.
    Electronic properties of vacancy-oxygen complexes in SiGe alloys2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 790-4Article in journal (Refereed)
    Abstract [en]

    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

  • 21. Molin, Yu N.
    et al.
    Ansinimov, O.A.
    Koptyug, A. V.
    Saik, V. O.
    Antzutkin, Oleg
    Effect of external magnetic fields and resonance radiofrequency radiation on radical reactions1990In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 164, no 1-2Article in journal (Refereed)
    Abstract [en]

    It is well known that an external magnetic field can affect the rate of singlet-triplet transitions in a radical pair and hence its recombination probability in liquid. Resonance radiofrequency (RF) radiation induces quantum beats in the kinetics of radical pair recombination. At high RF field amplitudes the singlet-triplet transitions in radical pairs can be efficiently suppressed (9 refs.)

  • 22.
    Murin, L.I.
    et al.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Lindström, J.L.
    Department of Physics, Lund University.
    Markevich, V.P.
    Centre for Electronic Materials, University of Manchester.
    Hallberg, T.
    Defence Research Establishment, Linköping.
    Litvinov, V.V.
    Belarusian State University, Minsk.
    Coutinho, J.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Isotopic effects on vibrational modes of thermal double donors in Si and Ge2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, p. 290-293Article in journal (Refereed)
    Abstract [en]

    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.

  • 23.
    Pinho, N.M.C.
    et al.
    School of Physics, University of Exeter.
    Torres, V.B.
    Department of Physics, University of Aveiro.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    Department of Physics, University of Newcastle.
    Mg-H and Be-H complexes in c-BN2001In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 308, p. 1027-30Article in journal (Refereed)
    Abstract [en]

    Ab initio calculations on hydrogen complexes with Mg and Be impurities in c-BN are reported. We find that both impurities are acceptors and bind H to form passive defects. However, their structures are different. For Be-H, the H atom lies at a puckered bond centre configuration similar to C-H in GaAs, while in Mg-H the H atom lies at an anti-bonding site to an N neighbour of the impurity. The hydrogen related vibrational modes of the two complexes are also reported.

  • 24. Rayson, Mark
    et al.
    Goss, J. P.
    Briddon, P. R.
    First principles calculation of zero-field splitting tensors2003In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 340, p. 673-676Article in journal (Refereed)
  • 25.
    Savini, Gianluca
    et al.
    University of Sussex.
    Savini, Giancarlo
    University of Sussex.
    Marocchi, Angela
    University of Bologna.
    Suarez-Martinez, Irene
    University of Sussex.
    Haffenden, Gemma
    University of Sussex.
    Heggie, Malcolm I.
    University of Sussex.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Anomaly enhancement of the dislocation velocity in SiC2007In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 401-402, p. 62-66Article in journal (Refereed)
    Abstract [en]

    Under forward bias SiC p-i-n diodes exhibit an anomaly enhancement of the partial dislocation mobility. Through first-principle calculations, we have shown that Peierls barriers and electrical activities are strongly dependent on the dislocation core structures. Further we have found that solitons or antiphase defects along the dislocation line cannot explain alone the enhancement of the dislocation velocity. We have proposed a new theoretical model that can explain the enhancement of the dislocation mobility under forward bias. This model can be applied to any semiconductor materials in order to predict the behaviour under electron-hole plasma injections.

  • 26.
    Sque, S.J.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    University of Newcastle Upon Tyne.
    Transfer doping of diamond: the use of C60 and C60F36 to effect p-type surface conductivity2006In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 376, p. 268-71Article in journal (Refereed)
    Abstract [en]

    Ab initio density-functional theory is used to determine the suitability for transfer doping of diamond surfaces with various hydrogen and oxygen terminations. Transfer doping of the hydrogenated (0 0 1) diamond surface with C60 is investigated, and electron transfer from diamond to C60 (leaving a hole layer near the diamond surface) is predicted for a C60 coverage of about one monolayer. The efficiency of electron transfer is expected to increase for higher coverages. It is also shown that the greater electron affinity of fluorinated C60 is likely to enhance the effect, in that C60F36 can extract electrons from hydrogenated diamond at much lower coverages. The consequences of oxygenation of the diamond surface on the transfer-doping properties of C60 are also investigated

  • 27.
    Torres, V.J.B.
    et al.
    Department of Physics, University of Aveiro, Campus Santiago.
    Coutinho, J.
    Department of Physics, University of Aveiro, Campus Santiago.
    Jones, R.
    School of Physics, University of Exeter.
    Barroso, M.
    Department of Physics, University of Aveiro, Campus Santiago.
    Öberg, Sven
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Early SiO2 precipitates in Si: vacancy-oxygen versus interstitial-oxygen clusters2006In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 376-377, no 1, p. 109-112Article in journal (Refereed)
    Abstract [en]

    Oxygen precipitation in Si strongly depends on the undergoing thermal treatment. Between 350 and 450 °C thermal donor formation is activated by a 1.4-1.6 eV barrier. On the other hand, at T>500°C, SiO2 cluster formation is limited by the interstitial oxygen (Oi) migration barrier of ∼2.5eV. Volumetric arguments imply that the formation of silica precipitates during anneals of oxygen-rich Si crystals, must be accompanied by the ejection of approximately one Si self-interstitial (Sii) per SiO 2 unit that is formed. We report on ab-initio density-functional studies of small oxygen aggregates in Si, to show that the On→VOn+Sii reaction is exothermic for n≥4. The large energy barrier required to form an intermediate Sii defect prevents the formation of VOn complexes at temperatures as low as 450 °C. Our results imply that thermal donors are not thermodynamically stable clusters, and their formation is driven by kinetics. Infra-red absorption studies can discriminate VOn and On defects. We report their local vibrational modes and compare them with the available experimental data

  • 28. Weber, Hans
    et al.
    Minnhagen, Petter
    Non-universal Kosterlitz-Thouless jumps and two-dimensional XY-type models1988In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 152, no 1-2, p. 50-55Article in journal (Refereed)
    Abstract [en]

    Renormalization equations for the Kosterlitz-Thouless vortex-unbinding transition indicate that this transition may be either continuous and of infinite order ("usual" Kosterlitz-Thouless transition) or discontinuous (non-universal jumps, etc.). Results from Monte Carlo simulations aiming at verifying the existence of both these possibilities for two-dimensional XY-type models are reported.

1 - 28 of 28
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