Revisiting the impact of single-vacancy defects on electronic properties of graphene

While defects are generally considered to be unavoidable in experiments, engineering them is a way of manipulating the physical properties of materials. Aiming to find a link between the location of single-vacancy (SV) defects and the resulting electronic band structure, we studied periodically arranged SV defects in graphene using the tight-binding method. Results show that SV defects can exhibit predictable electronic behavior when they reside on the same sublattice, following the electronic band structure of the armchair graphene nanoribbons (AGNRs) depending on the spacing between SVs, meaning the linear bands of graphene can be restored. AGNRs are known for their tunable electronic bandgap. However, when SVs are located on different sublattices, the interaction between the defect-induced states becomes strong and can introduce anisotropy into the electronic band structure, demonstrating that the relative position of the SVs can also act as an additional degree of freedom for tuning the electronic properties. Interestingly, the behavior is independent of the density of SVs; for a system fully defected with SVs, the electronic properties depend heavily on the sublattices involved.