The electronic transport properties of armchair carbon nanotubes with single and multiple horizontal boron-nitride lines: Unusual effects of high bias voltage on I-V characteristics

Abstract

We investigate the electronic band structure properties for different arrangements of infinite horizontal boron nitride (BN) lines in the (6,6) armchair carbon nanotube. Depending on the arrangement of the boron and nitrogen atoms, the horizontal BN lines can be viewed as single or multiple BN segments along the contour of the host carbon nanotube. According to the geometrical orientation of the BN segment(s) in the circular direction, the band gap energy can be tuned providing semiconducting properties for the parallel geometries and metallic behaviors for the antiparallel geometries respectively. For the non-equilibrium transport properties, the current-voltage characteristics for such structures are also examined. Conventional fluctuations in the current are obtained for the high bias voltage as a sign of the resonant tunneling effects in the electronic transport process. However, unusual current-voltage characteristics are reported for particular BN segment configurations in the anti-parallel multiple geometry. The transmission functions and the local currents are respectively presented pointing out more details about such discrepancy in both the electronic transport process near the Fermi level and the nature of the corresponding wave functions. All calculations are performed by means of the density functional tight-binding approach as implemented in the DFTB+ software package.