Dirac gap-induced graphene quantum dot in an electrostatic potential

Abstract

A spatially modulated Dirac gap in a graphene sheet leads to charge confinement, thus enabling a graphene quantum dot to be formed without the application of external electric and magnetic fields [Appl. Phys. Lett. \textbf{97}, 243106 (2010)]. This can be achieved provided the Dirac gap has a local minimum in which the states become localised. In this work, the physics of such a gap-induced dot is investigated in the continuum limit by solving the Dirac equation. It is shown that gap-induced confined states couple to the states introduced by an electrostatic quantum well potential. Hence the region in which the resulting hybridized states are localised can be tuned with the potential strength, an effect which involves Klein tunneling. The proposed quantum dot may be used to probe quasi-relativistic effects in graphene, while the induced confined states may be useful for graphene-based nanostructures.Comment: 12 pages, 7 figure