Scanning Tunneling Microscopy and Spectroscopy of Rotated Phases on C-Face Epitaxial Graphene

Diffraction data have shown that multilayer graphene grown on the (000-1) polar face of SiC forms with a high density of rotational stacking faults [1]. We present STM evidence of these rotated phases along with rationale for the particular angles observed. Topographic images show flat, micron scale domains with surface modulation periods corresponding to moir\'{e} patterns generated by rotational stacking faults near the surface. The modulation periods are in agreement with surface x-ray diffraction and low energy electron diffraction data. STS data will be presented and the effects of the observed rotated domains on the electronic structure of C-face multilayer graphene films will be discussed. [1] J. Hass, F.Varchon, J. E. Mill\'{a}n-Otoya, M. Sprinkle, W.A. de Heer, C. Berger, P.N. First, L. Magaud, E.H. Conrad (\textit{to be published}), http://arxiv.org/abs/0706.2134