Bogolyubov Institute for Theoretical Physics, NAS of Ukraine, 14b Metrolohichna Str., Kiev 03680, Ukraine
IFIMUP/Departamento de Fisica, Universidade do Porto, R. Campo Alegre, 687, Porto, 4169-007, Portugal
Received May 15, 2012
A Green function analysis has been developed for quasiparticle spectrum of a 2D graphene sheet in presence of different types of substitutional disorder, including vacancies. The anomalous character of impurity effects in this system is demonstrated, compared to those in well known doped semiconductors, and explained in terms of conical singularities in the band spectrum of pure graphene. The criteria for appearance of localized states on
clusters of impurity scatterers and for qualitative restructuring of band spectrum are established and a possibility for a specific metal/insulator transition at presence of vacancies is indicated.
PACS: 03.65.Pm Relativistic wave equations; PACS: 71.30.+h Metal-insulator transitions and other electronic transitions; PACS: 71.55.–i Impurity and defect levels.
Key words: graphene, quasiparticle spectrum, impurity and vacancy effects.