Electronic Structures of BC2N Nanoribbons

We reveal a rich variety of electronic and magnetic properties of H-terminated BC2N nanoribbons (BC2NNRs) by using extensive first-principles calculations. Zigzag edged BC2NNRs (z-BC2NNRs) can be semiconducting or metallic depending on the alignment of edge atoms. In particular, magnetic and even half-metallic behaviors can appear in some edged z-BC2NNRs when the ribbon width is over a critical value. Armchair-edged BC2NNRs also can be semiconducting or metallic but determined by the proportion of carbon, nitrogen, and boron atoms in the ribbons. The band gaps of all semiconducting BC2NNRs can be explained by a universal mechanism that is due to the charge polarization between the opposite edges, which is impaired with increasing ribbon width.