MICROSCOPY Vol.46▶No.1 2011
â– Seto Award

Creation and structure control of carbon nanotube and graphene by SiC suface decomposition

Michiko Kusunoki

Abstract: Carbon nanotubes (CNTs) and graphene derived from SiC(0001) and (0001) substrates respectively were investigated by transmission electron microscopy (TEM).
Formation of well-aligned and highly-dense CNT films by surface decomposition of SiC(0001) were firstly found. Growth mechanism of the CNTs was shown by clarifying the relationship between the diameter and number of the layer. Transmission electron diffraction patterns revealed that zigzag-type CNTs are selectively formed by the present method.
Successively, atomic-scale structures of the interface between graphene and SiC(0001) have been investigated using high-resolution TEM observation combined with a first principles calculation. Our analysis revealed the presence of a metastable transitional structure formed by decomposition of a single SiC bilayer as well as fully-packed honeycomb graphene as the interface structure. The results of our calculation clarified that the difference in the interface structures should strongly influence the electronic states. A formation process of graphene layers on SiC (0001) were also revealed by high-resolution TEM as following: Initially, nucleation occurs at SiC steps, covering them with a few layers of graphene. These curved graphene layers stand almost perpendicularly on the lower terrace. Graphene subsequently grows over the terrace region. The growth is often pinned by lattice defects of the SiC substrate.

Key words: carbon nanotube, graphene, SiC, interface structure, TEM