Rotational stacking and its electronic effects on graphene films grown on 4H-SiC (000 1 ¯ )
J. Hass, F.Varchon, J. E. Millan-Otoya, M. Sprinkle, W.A. de Heer, C. Berger, P.N. First, L. Magaud, E.H. Conrad
Abstract
We examine the stacking order of multilayer graphene grown on the SiC
(000
1
¯
)
surface using low-energy electron diffraction and surface X-ray diffraction. We show that the films contain a high density of rotational stacking faults caused by three types of rotated graphene: sheets rotated
30
∘
and
±
2.20
∘
relative to the SiC substrate. These angles are unique because they correspond to commensurate phases of layered graphene, both with itself and with the SiC substrate. {\it Ab intio} calculations show that these rotational phases electronically decouple adjacent graphene layers. The band structure from graphene at fault boundaries displays linear energy dispersion at the
K
-point (Dirac cones), nearly identical to that of a single graphene sheet.