Quantum Mechanical Modeling of the Structure and Doping Properties of Defects in Diamond

The extreme materials properties of diamond lend it to a range of semiconductor applications, but the difficulty in forming n-type diamond, and the unintentional inclusion of deleterious impurities has proved problematic. Co-doping diamond with boron and deuterium yields n-type conduction and recent theory suggests that BD₂ and BD₃ complexes have shallow donor levels. We show here that the proposed structures are unstable and structural relaxation result in deep levels or passive defects. We also comment on other proposed co-doping schemes: N-H-N, S-H and Si₄-N. Finally we show that combination of theory and the polarized uptake of Ni in diamond contradict the current interstitial Ni models for the 1.404 eV center.