Papers by Keyword: Defect Reactions

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Authors: Aurangzeb Khan, Umar S. Qurashi, N. Zafar, M. Zafar Iqbal, Armin Dadgar, D. Bimberg
Authors: N.M. Johnson, C. Herring
Authors: P. Kaczor, L. Dobaczewski, T. Gregorkiewicz, C.A.J. Ammerlaan
Authors: Hartmut Bracht, S. Brotzmann, Alexander Chroneos
Abstract: We report experiments on the diffusion of n-type dopants in isotopically controlled Ge multilayer structures doped with carbon. The diffusion profiles reveal a strong aggregation of the dopants within the carbon-doped layers and a retarded penetration depth compared to dopant diffusion in high purity natural Ge. Dopant aggregation and diffusion retardation is strongest for Sb and similar for P and As. Successful modeling of the simultaneous self- and dopant diffusion is performed on the basis of the vacancy mechanism and additional reactions that take into account the formation of carbon-vacancy-dopant and dopant-vacancy complexes. The stability of these complexes is confirmed by density functional theory calculations. The overall consistency between experimental and theoretical results supports the stabilization of donor-vacancy complexes in Ge by the presence of carbon and the dopant deactivation via the formation of dopant-vacancy complexes. These results help to develop concepts to suppress the enhanced diffusion of n-type dopants and the donor deactivation in Ge. Both issues hamper the formation of ultra shallow donor profiles with high active dopant concentrations that are required for the fabrication of Ge-based n-type metal oxide semiconductor field effect transistors.
Authors: Richard A. Morrow
Authors: H. Feichtinger, E. Sturm
Authors: Vladimir P. Markevich, Anthony R. Peaker, I.F. Medvedeva, Vasilii E. Gusakov, L.I. Murin, Bengt Gunnar Svensson
Abstract: The influence of Cu contamination on radiation-induced defect reactions in n-type Czochralski-grown silicon (Cz-Si) crystals has been studied by means of the Hall effect technique, deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS with supporting theoretical modeling of defects. It is found that the contamination of Cz-Si samples with Cu does not influence significantly the energy spectrum and introduction rates of the principal electrically active defects induced by electron irradiation. The vacancy-oxygen (VO) centre, divacancy (V2) and a complex consisting of a silicon self-interstitial with the oxygen dimer (IO2) are found to be the dominant radiation-induced defects in Cu-contaminated samples as well as in uncontaminated ones. An isochronal annealing study has shown that the presence of Cu affects the annealing behaviour of the vacancy-related defects. In Cu-doped samples the VO centre disappears upon annealing at significantly lower temperatures (175-250°C) compared to those of the VO disappearance in the uncontaminated samples (300-375°C). The disappearance of the VO centres in the Cu-doped samples occurs simultaneously with an anti-correlated introduction of a defect with an energy level at about Ec- 0.60 eV. It is suggested that this defect is formed by the interaction of a mobile Cu atom with the VO complex. According to results of quantum-chemical modelling, in the most stable configuration of the Cu-VO defect a Cu atom occupies a tetrahedral interstitial position nearest to the elongated Si-Si bond of the VO centre. The presence of the Cu atom is found to result in the further elongation of the Si-Si bond and a shift of the VO acceptor level to the middle of the gap. The annealing behaviour of V2 has also been found to be different in the irradiated Cu-doped samples compared to that in the uncontaminated ones. The most probable reason for this difference is an interaction of mobile Cu atoms with di-vacancies. An energy level at about Ec-0.17 eV has been tentatively assigned to a complex consisting of a Cu atom and a di-vacancy.
Authors: El-Maghraby Mohamed, Yuzo Shinozuka
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