Growth temperature dependent graphene alignment on Ir(111)

The morphology of graphene monolayers on Ir(111) prepared by thermal decomposition of ethylene between 1000 and 1530 K was studied with high resolution low energy electron diffraction. In addition to a well-oriented epitaxial phase, randomly oriented domains are observed for growth temperatures between 1255 and 1460 K. For rotational angles of +/- 3 degrees around 30 degrees these domains lock-in in a 30 degrees oriented epitaxial phase. Below 1200 K the graphene layer exhibits high disorder and structural disintegrity. Above 1500 K the clear moire spots reflect graphene in a single orientation epitaxial incommensurate phase. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3548546]