▎ 摘　　要

Transmission electron microscopy (TEM) investigations of epitaxial graphene, grown on on-axis and 8 degrees off-axis C-terminated 4H-SiC (000 (1) over bar) surfaces are presented. The TEM results provide evidence that the first carbon layer is separated by 3.2 angstrom from the C-terminated SiC surface. It was also found that thick graphene layers grown on on-axis SiC (000 (1) over bar) are loosely bound to the SiC substrate. Moreover, the structural observations reveal a certain degree of disorder between the graphene planes, which manifests itself in a rotation of the layers and in an increase in the interplanar spacing between certain carbon layers from 3.35 angstrom, which is characteristic for graphite, up to 3.7 angstrom. Graphene grown on 8 degrees off-axis SiC (000 (1) over bar) substrates covers the steps of SiC and as a result disorder seems to be not as pronounced as it is on the on-axis SiC (000 (1) over bar) substrate. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3445776]