Influence of orientation angles on field emission characteristics of boron nanotubes: a theoretical study

The field emission characteristics of tilted nanomaterials depend notably on their inclination angles. Therefore, in this paper, the significant influence of orientation angles (OAs for short) on field emission characteristics of a capped (5, 5) boron nanotube (BNT) was investigated using density functional theory calculations. Their work functions with different OAs decreased linearly with applied electric fields, and emission currents increased distinctly with external electric fields. There was a small difference among these work functions under lower electric fields. However, distinctions of work functions and emission currents were enlarged while the external fields ranged from-0.1 V/angstrom to higher value. The emission currents of the (5, 5) BNT under applied electric fields were comparable to that of carbon nanotubes (CNTs) under the same electric fields, and the apex of the (5, 5) BNT were the highest probable positions for electron emission. The tunneling probability of the pristine (5, 5) BNT with OA=0 reached maximum value, so that the BNTs perpendicular to the substrate would achieve the largest emission current.