Deep hydrogen traps in heavily B-doped diamond

Exposure of heavily B-doped (2×10¹⁹--4×10²⁰cm^-3) diamond to a deuterium plasma results in the formation of passive B-D complexes which are bound with a dissociation barrier of 2.5 eV. In heavily doped material there is evidence that deeper deuterium traps exist. Using first-principles methods we show that nearest-neighbor boron pairs are bound and can efficiently trap deuterium. The calculated binding energy for the B-D pair is in good agreement with experimentally obtained values. The comparison of the measured deuterium and boron concentrations with the model suggest that boron dimers are deeper deuterium traps, but complementary infrared or Raman measurements are needed to draw absolute conclusions regarding the formation of B₂D or B₂D₂ complexes.