First-principles calculation of effects of deformation and electric field action on electrical properties of Graphene

Abstract

Based on the first-principles method of density functional theory, a systematic research is conducted on the electron mechanism of the effect of deformation, electric field action and combined action on the electrical properties of graphene. The research results show that the energy gap and density of states of graphene are both 0 at the Fermi level, indicating semi-metallic character, which implies that the calculation model and the parameter setting are reasonable in this paper. After some deformation actions, such as shear, stretch, torsion and bending deformation on the graphene, it is found that shear and torsion exert an obvious effect on opening the energy gap of graphene, but the effects of tensile and bending deformation on the energy gap of graphene are negligible. Therefore, shear deformation and torsion deformation are a preferred alternative to controlling the energy gap of graphene. By adding the electric field to the graphene in different directions, it is found that the , and direction electric fields which are parallel to the plane of graphene exert a strong effect on opening the energy gap of graphene, but the effect of direction electric field which is perpendicular to the plane of graphene is weak. Especially, the direction electric field has the strongest effect on opening the energy gap of the graphene because the positive value of the population of graphene C–C atoms in the direction is relatively large and bond energy is high while the negative value is small and the antibond energy is low. In order to investigate the influence of electric field strength on energy gap of graphene, the electric field strength is increased linearly from 0.1 eV/Å/e to 0.5 eV/Å/e. It can be observed that the energy gap of graphene increases in turn, and shows a linear growth. Under the action of 0.1 eV/Å/e electric field strength, shear deformation, stretch deformation, torsion deformation and bending deformation take place on the grapheme. It is found that under the combined action of deformation and electric field, the electric field improves the effect of deformation on the energy gap, but the effect is not so good asunder the superposition of two fields.