فهرست نشریات علمی دسترسی آزاد ایران

In this paper, we calculate the band structure of graphene using the empirical tight-binding (TB) method with a first-neighbor approximation and an SP 2 basis. Subsequently, utilizing the same first-neighbor approximation SP 2 basis for electron and gap levels, we obtain the energy of graphene nanodiscs (GNDs) with varying radii. As expected, the calculated energy gap decreases with an increase in the radius of the nanodisc. Finally, the energy gap of a nanodisc with a huge radius converges to the energy gap of two-dimensional graphene. Our numerical results indicate that the energy gap is dependent on the shape of the edges and the radius of the GND. Controlling the energy gap by applying an external field is beneficial for optical, infrared, and THz applications. Here, using the empirical tight-binding method for π-electrons, we have estimated the effect of an external electric field on a set of nanodiscs. The application of an external electric field and its impact on the energy gap are key factors in controlling the energy gap of nanodiscs.