Metal-semiconductor (semimetal) superlattices on a graphite sheet with   vacancies
  It has been found that periodically closely spaced vacancies on a graphite sheet cause a significant rearrange-ment of its electronic spectrum: metallic waveguides with a high density of states near the Fermi level are formed along the vacancy lines. In the direction perpendicular to these lines, the spectrum exhibits a semimetal or semiconductor character with a gap where a vacancy miniband is degenerated into impurity levels. 
L.A. Chernozatonskii, P.B. Sorokin, E.E. Belova, J. Bruning, and A.S.   Fedorov