Shape, width, and replicas of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>π</mml:mi></mml:math>bands of single-layer graphene grown on Si-terminated vicinal SiC(0001)

Abstract

Massless $\ensuremath{\pi}$ bands of graphene grown on a SiC(0001) substrate can be affected by the scattering at the boundaries and the interface superstructure. We investigated the $\ensuremath{\pi}$ band structure and width of the single- and double-layer graphenes grown on a vicinal SiC(0001) substrate using angle-resolved photoemission spectroscopy. The $\ensuremath{\pi}$ electron scattering at the substrate steps makes the spectrum width anisotropic but no difference occurs in the $\ensuremath{\pi}$ band shape. Quasi-$2\ifmmode\times\else\texttimes\fi{}2$ replicas of the $\ensuremath{\pi}$ band due to the interface $6\sqrt{3}\ifmmode\times\else\texttimes\fi{}6\sqrt{3}R30\ifmmode^\circ\else\textdegree\fi{}$ superstructure were observed in the single-layer graphene while they were absent in the double-layer graphene.