Tunable electronic properties of ultra-thin boron-carbon-nitrogen heteronanotubes for various compositions

A first-principles calculation was carried out to investigate the stability and electronic properties of ultra-thin Cx(BN)y heteronanotubes which were composed by joining pure CNT and BNNT segments with different composition and configurations. We found that the stability of Cx(BN)y heteronanotubes is increased with the increasing number of B and N atoms. In addition, all armchair (3,3) Cx|(BN)y heteronanotubes were found to be semiconductors with tunable energy gaps between 0.45 to 1.62 eV. Whereas zigzag (5,0) Cx|(BN)y heteronanotubes can be metal (y≤4) or semiconductor (y>4), and it is different from the relatively big zigzag Cx|(BN)y heteronanotubes which are always conductors. It indicates that the energy gap of (5,0) Cx|(BN)y heteronanotubes can be tuned by modifying the value of y. Further, zigzag (5,0) and armchair (3,3) C-BN heteronanotubes were found to be metal and semiconductor, respectively; but zigzag and armchair C-BN heteronanotubes with relatively big diameter are always semiconductor and conductor, respectively. Therefore, the electronic properties of ultra-thin Cx(BN)y heteronanotubes are abnormal when comparing with the relatively big ones. Highlights• The stability of Cx(BN)y heteronanotubes is increased with the increasing value of y.• Zigzag (5,0) Cx|(BN)y heteronanotubes can change from metal (y≤4) to semiconductor (y>4) when the value of y increases from 1 to 7.• The band gaps of armchair (3,3) Cx|(BN)y heteronanotubes increase from 0.45 to 1.62 eV when the value of y increases from 1 to 7.• The electronic properties (energy gap) of Cx(BN)y heteronanotubes are tunable and different in comparison with the relatively big ones.