Electronic structures of N-doped graphene with native point defects

Hou, Z.*; Wang, X.*; Ikeda, Takashi; Terakura, Kiyoyuki*; Oshima, Masaharu*; Kakimoto, Masaaki*

We have performed the DFT calculations to study the electronic structures of N-doped graphene with vacancies and Stone-Wales defect. Our results show that monovacancies in graphene act as hole dopants and that two substitutional N dopants are needed to compensate for the hole introduced by a monovacancy. On the other hand, divacancy does not produce any free carriers. Interestingly, a single N dopant at divacancy acts as an acceptor rather than a donor. Compared with the case of an isolated N dopant in perfect graphene, the electrons donated by substitutional N dopants would be localized significantly when a N-N pair is formed. The N-N interaction and the interference between native point defect and N dopant strongly modify the role of N doping regarding the free carrier production in the bulk bands. Our results are qualitatively consistent with the experimental observation that the concentration of free electrons introduced by N dopants would be lower than that of doped N.