Vacancy-induced shifts of edge states in Z-shaped graphene nanoribbon quantum dot

Abstract

Quasi-one-dimensional quantum dot consisting of Z-shaped graphene nanoribbon junction, is known to create discrete edge states in the bandgap due to quantum confinement effect depending on the length of the quantum dot. To examine possible changes in the midgap states caused by introducing a carbon vacancy within the quantum dot, we calculated the band structures of the defective systems using density functional based tight-binding method, and also using a simplest tight-binding model for π-electrons. As the central result, we predict that the separation of midgap edge states are considerably variable, depending on the choice of a vacancy site. The transmission via midgap edge states and zero-mode state is shown.