Boron-hydrogen complexes in diamond: Energy levels and metastable states

The shallow n-type doping of boron doped diamond with an excess of deuterium has attracted considerable attention. However, despite numerous studies, the nature of this donor is the subject of continued debate. We show that BH2 possesses a substantial number of metastable states, which are likely to play a role in the properties of the BH2 defect, and that it is possible in principle for these higher energy metastable structures to be reached. The levels induced by these metastable BH2 defects are shown to be shallower than the original deep BH2 levels, but still deeper than the experimentally observed donor levels. We also report spin density distributions of BH2 centres, which may be compared with experiment, towards establishing the nature of the new donor. (C) 2009 Elsevier B.V. All rights reserved.