Papers by Keyword: Transition Metal Impurities

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Authors: Johann Martin Spaeth, Siegmund Greulich-Weber, M. März, J. Reinke, M. Feege, E.N. Kalbukhova, S.N. Lukin
Authors: E.P. Skipetrov, M.M. Markina, K.V. Zakharov, L.A. Skipetrova, A.A. Solovev, A.V. Knotko, E.I. Slynko, V.E. Slynko
Abstract: The galvanomagnetic properties in weak magnetic fields (4.2≤T≤300 K, B≤0.07 T) as well as magnetic properties (2≤T≤300 K, B≤9 T) of the single-crystal Pb1-yScyTe (y≤0.02) alloys have been investigated. We find that an increase of Sc impurity content leads to a monotonous growth of the free electron concentration (from 1016 cm-3 to 1020 cm-3). In heavily doped alloys (y>0.01), it tends to saturation, indicating the pinning of the Fermi energy by the scandium resonant level located inside the conduction band. The energy of the level is estimated (ESc≈Ec+280 meV) and the model of electronic structure rearrangement of Pb1-yScyTe alloys with doping is proposed. In the frame of this model, using experimental temperature and magnetic field dependences of magnetization, the concentrations of magnetically active scandium ions are determined and connection of the electronic structure with the magnetic properties of the alloys are discussed.
Authors: Nguyen Tien Son, Viktor Ivády, Adam Gali, Andreas Gällström, Stefano Leone, Olof Kordina, Erik Janzén
Abstract: In unintentionally Nb-doped 4H-SiC grown by high-temperature chemical vapor deposition (HTCVD), an electron paramagnetic resonance (EPR) center with C1h symmetry and an electron spin S=1/2 was observed. The spectrum shows a hyperfine structure consisting of ten equal-intensity hyperfine (hf) lines which is identified as due to the hf interaction between the electron spin and the nuclear spin of 93Nb. An additional hf structure due to the interaction with two equivalent Si neighbors was also observed. Ab initio supercell calculations of Nb in 4H-SiC suggest that Nb may form complex with a C-vacancy (VC) resulting in an asymmetric split-vacancy (ASV) defect, NbSi-VC. Combining results from EPR and supercell calculations, we assign the observed Nb-related EPR center to the hexagonal-hexagonal configuration of the AVS defect in the neutral charge state, (NbSi-VC)0.
Authors: M. Surma, A.J. Zakrzewski, M. Godlewski
Authors: Jörg Weber, Leopold Scheffler, Vladimir Kolkovski, Nikolai Yarykin
Abstract: In silicon several electronic levels are known which can be attributed to transition metals. Ignorance persists however about the specific nature of the defect centers. Some progress was made recently on identifying electronic levels from substitutional or interstitial lattice sites and on identifying levels from defect complexes. The sensitive Laplace DLTS technique allows us to determine depth profiles or the influence of the electrical field on the emission rate with unparalleled accuracy. Three examples will be discussed in this short review: The identification of the CoB pair, a reinterpretation of the Ti DLTS spectrum and the complex formation of interstitial Cu with substitutional Cu as the nucleation site.
Authors: T. Telahun, P. Thurian, Andreas Hoffmann, I. Broser, Udo Scherz
Authors: J. Schöpp, R. Heitz, Andreas Hoffmann, Udo Scherz
Authors: Shazia Parveen, Aurangzeb Khan, Umar S. Qurashi, N. Zafar, M. Zafar Iqbal, L. Köhne, Armin Dadgar, D. Bimberg
Authors: P. Głód, T. Dietl, T. Fromherz, H. Krenn, G.H. Bauer, I. Miotkowski
Authors: Rui Xun Zou, Da Chuan Jiang, Wei Dong, Zheng Gu, Yi Tan
Abstract: The electron beam injection (EBI) process involves offering electrons around silicon powder, whose surface was oxidized, and subsequently the powder is washed by HF acid so as to remove the SiO2 film. The new electron beam injection process, in which micro electric filed formed between Si and SiO2 film will accelerate impurities diffusion from Si to SiO2 film, was developed and applied to eliminate the transition-metal impurities of MG-Si. It is proved to be effective to remove transition-metal impurities from metallurgical grade silicon (MG-Si). By applying the electron beam injection method, the removal rate of 10% to 59% was achieved during the refining process. The efficiency of impurity removal originates from two aspects: the impurity concentration gradient on both sides of Si/SiO2 interface; the micro electric field formed from Si to SiO2 film. A further increase in the removal rate can be realized by controlling the processing parameters.
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