First principles studies of H in diamond

JP Goss, R Jones, MI Heggie, CP Ewels, PR Briddon and S Öberg
Physica Status Solidi A

Ab initio methods are used to investigate hydrogen defects in diamond. For the isolated impurity, the bond-centered site is found lowest in energy and posses both donor and acceptor levels. The neutral defect possesses a single local mode with 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*
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 in rasonable agreement with experiment. Hydrogen is strongly bound to dislocations which, together with H*
may form part of the hydrogen accumulation layer detected in some plasma studies.

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