  The influence of edge vacancies on the working ability of the planar graphene
tunnel field-effect transistor (TFET) is studied at various concentrations and
distributions (normal, uniform, periodic) of defects. All calculations are
performed by using the Green's function method and the tight-binding
approximation. It is shown that the transistor performance depends critically
on two important factors associated with the defects: the destruction of the
edge-localized electronic states and the emergence of subpeaks near the Fermi
level. The supportable operation conditions of the TFET are found to be ensured
at 30 percent or less of edge vacancies regardless of the type of their
distribution.
