Quasiparticle band gaps of boron nitride nanoribbons

Abstract

We present a systematic study on the quasiparticle band gaps of armchair boron nitride nanoribbons (ABNNRs) as a function of the ribbon width, using a first-principles many-body approach based on the $GW$ approximation. Because of the quasi-one-dimensional nature of ABNNRs, the enhanced Coulomb interaction effects and the reduced screening greatly influence the quasiparticle band gaps, giving rise to the $GW$ correction in a range 2.5--3.0 eV. A comparative study on the edge structures of ABNNRs reveals that the band gaps of the hydrogen-terminated ABNNRs are direct and have apparent family dependence, while those of the bare ABNNRs are indirect and have no family dependence. This is consistent with the conclusion obtained by density functional theory (DFT) within the local-density approximation. Our $GW$ calculations validate the qualitative correctness of the DFT study on BNNRs, together with the demonstration of the necessity of many-body approaches for quantitative understanding of quasiparticle band gaps.