C-chain-doping induced band-state transition in armchair AlN nanoribbons

Little is known about the band states of armchair AlN nanoribbons (aAlNNRs), so we investigated their band states of perfect and single C-chain-doped aAlNNRs by first-principles calculations. For aAlNNRs with a width N < 12, the nonedge C-chain doping can lead to the distribution of the conduction-band minimum (CBM) electrons transferring from the central part of the ribbon to the C–N–Al ring. One representative model for aAlNNRs with a width of 8 ([aAlNNR]₈) was mainly studied. In contrast to a h-AlN monolayer, we find a second degenerate state (above the Fermi level) in perfect [aAlNNR]₈, which stems from the Al-s p_y and hybridized N-s p_z orbitals. However, both degenerate states are suppressed by single C-chain doping. For N ≥ 12, wherever a C-chain locates, the CBM always displays similarly delocalized characteristics. Our study can not only show that single C-chain doping can significantly modify the band states, but also can enrich the understanding of aAlNNRs.