▎ 摘　　要

First-principles calculations are performed to study the modulation of energy gaps in nitrogen delta-doping (N delta-doping) graphene and armchair-edge graphene nanoribbons (AGNRs). The energy gap of graphene only opens at a large nitrogen doping content. For AGNRs, the energy gaps tend to decrease with the N delta-doping, and an interesting transition from direct to indirect bandgap is observed. Moreover, the effects of N delta-doping on energy gaps incline to decease with the reduction of the doping content. Our results may help to design novel graphene-based nanoelectronics devices by controlling N delta-doping of graphene. (C) 2011 American Institute of Physics. [doi:10.1063/1.3609243]