Lookup NU author(s): Dr Jon Goss,
Professor Patrick Briddon
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Ab initio cluster and supercell methods are used to investigate the local geometry and optical properties of hydrogen defects in diamond. For an isolated impurity, the bond-centered site is found to be lowest in energy, and to possess both donor and acceptor levels. The neutral defect possesses a single local mode with a very small infrared effective charge, but the effective charge for the negative charge state is much larger. H+ is calculated to be very mobile with a low activation barrier. Hydrogen dimers are stable as H-2* defects, which are also found to be almost IR inactive. The complex between B and H is investigated and the activation energy for the reaction B-H-->B- +H+ found to be around 1.8 eV in agreement with experiment. We also investigate complexes of hydrogen with phosphorus and nitrogen. The binding energy of H with P is too low to lead to a significant codoping effect. A hydrogen-related vibrational mode of the N-H defect, and its isotopic shifts, are close to the commonly observed 3107-cm(-1) line, and we tentatively assign this center to the defect. Hydrogen is strongly bound to dislocations which, together with H-2*, may form part of the hydrogen accumulation layer detected in some plasma studies.
Author(s): Goss JP, Jones R, Heggie MI, Ewels CP, Briddon PR, Oberg S
Publication type: Article
Publication status: Published
Journal: Physical Review B
ISSN (print): 1098-0121
ISSN (electronic): 1550-235X
Publisher: American Physical Society
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