Effect of excess hydrogen on the electronic properties of passivated diamond

Recently, Yan et al. reported a theoretical approach to overcome the n-type doping problem of diamond by passivating the B acceptor and the reduction of ionization energy of dopants. Using the proposed approach, we have systemically investigated the effect of excess H atoms on the electronic properties of a passivated system [diamond doped with (B+H) complex] based on the variation of Fermi level from first-principle calculations. The results show that the excess H atom is responsible for n-type behavior when all valence electrons of substitutional B atom participate in the hybridization between substitutional B and H atoms. On the contrary, when part of valence electrons of the substitutional B atom participates in the hybridization, H atoms make the passivated system show p-type or insulator behavior. Further study indicates that the excess H atoms are more apt to make the passivated system show p-type rather than n-type behavior under the same conditions. It leads to a much more comprehensive understanding of the interaction between the excess H atoms and the passivated system compared with that of Yan et al. The results may be useful to provide guidance for experimental work on obtaining n-type diamond in the future.