Carbon nanotubes with atomic impurities on boron nitride sheets under applied electric fields

We perform first-principles calculations to investigate the structural and electronic properties of metal-doped (10, 0) carbon nanotubes (CNTs) on a single hexagonal boron nitride (hBN) sheet in the presence of an external electric field. We consider K, Cl and Ni atoms as dopants to study the dependence of the electronic properties of the CNT on doping polarity and concentration. The electric field strength is varied from -0.2 V/\AA to +0.2 V/\AA to explore the effects of an external electric field on the electronic structures. Although the electronic energy bands of the hBN sheet are modified in accordance with the field strength, its electronic state in the valence or conduction band does not touch the Fermi level under the field strength considered. We conclude that the hBN as a substrate does not modify the electronic structure of the CNT, thereby leading to improvements in the device performance, compared with that of devices based on conventional substrate materials such as SiO$_2$.