Initial stage of carbon nanotube formation process by surface decomposition of SiC: STM and NEXAFS study

Formation process of carbon nanocaps, which are formed at the beginning of carbon nanotube (CNT) growth by surface decomposition of SiC, was investigated by scanning tunneling microscopy (STM) and in situ near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. As Si atoms were desorbed, carbon nanoparticles 1-2 nm in diameter were accumulated on SiC(000-1) surfaces. At around 1200 °C, these were coalesced and crystallized to carbon nanocaps. In addition, just before the crystallization, majority of C-C bonds were directed nearly parallel to the surface. Based on these experimental results, we proposed a model for carbon nanocap formation, which plays an important role to determine the CNTs.