Scanning probe analysis of twisted graphene grown on a graphene/silicon carbide template

Overlayer growth of graphene on an epitaxial graphene/silicon carbide (SiC) as a solid template by ethanol chemical vapor deposition is performed over a wide growth temperature range from 900 °C to 1450 °C. Structural analysis using atomic force and scanning tunneling microscopies reveal that graphene islands grown at 1300 °C form hexagonal twisted bilayer graphene as a single crystal. When the growth temperature exceeds 1400 °C, the grown graphene islands show a circular shape. Moreover, moiré patterns with different periods are observed in a single graphene island. This means that the graphene islands grown at high temperature are composed of several graphene domains with different twist angles. From these results, we conclude that graphene overlayer growth on the epitaxial graphene/SiC solid at 1300 °C effectively synthesizes the twisted few-layer graphene with a high crystallinity.