Control of rotation angles of multilayer graphene on SiC (000-1) by substrate off-direction and angle.

Graphene on SiC (000-1) tends to grow in multiple layers and does not have a single orientation relation with the SiC substrate. It has been considered impossible to control the rotation angle of multilayer graphene on SiC (000-1). In this study, we grew graphene on off-axis SiC substrates with various off angles from 0° to 8° and investigated their in-plane rotation and electronic structures systematically. As the off angle toward the [11-20]direction increased, graphene rotated by 30° with respect to SiC became less dominant and instead, graphene rotated by 30 ± 2.5° appeared. We also found that the uniformity of the graphene rotation angle was relatively high on SiC substrates with a small off angle toward the [1-100]direction. Our results suggest that the step-terrace structure defined by the substrate off-direction and angle plays an important role in the controllability of the rotation angle of graphene.