First-principle study on energy gap of CNT superlattice structure

By using the CASTEP modules based on density functional theory, the electronic structures of B/N pair co-doping (5, 5) CNT rings superlattice have been investigated. The calculation results show that the formation energies of B/N pair co-doping CNT rings are negative, indicating that the new type construction will probably be stable. The band structure and state density of the new type construction show that the energy gap is opened by B/N co-doping in (5, 5) metallic CNT and the metallic CNT is changed into a semiconductor. The energy gap of pure CNT is strongly sensitive to the changes of CNT diameter but the energy gap of B/N co-doping CNT rings remains stable when the diameters are in a reasonable scope, which means that the requirements for the production of CNT have been reduced. The compressive deformation effects mean that the energy gaps are narrowed, which is equivalent to enhancing the doping volume concentration. However, the changes of the energy gap under the tensile deformation effect are opposite. Achieving control of the electrical conductivity of CNT has an important significance for electron devices.