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Nanosized cap structures on a thermally treated 6H-SiC(000 1 1) substrate were investigated using atomic-resolution ultrahighvacuum scanning tunneling microscopy (UHV-STM). Hexagonal carbon networks, partly composed of pentagons, were clearly observed on the surface of the cap structures for a sample annealed at 1250 C, in which carbon nanotubes (CNTs) had negligibly grow into the SiC substrate. Comparing their sizes and shapes with those annealed at 1350 C, the cap structures were considered to be the initial state of carbon nanotube (CNT) growth which determines the tube diameters of the final grown CNTs.

Figure 4. Detection of the extent to which the combined therapies inhibited cancer cells.

The Raman spectra of carbon nanotubes (CNTs) formed on a 6H–SiC(0001) C-face substrate by surface decomposition were acquired using a 1064 nm Nd:YAG laser as the excitation source. Intense radial-breathing-mode Raman bands were successfully detected under resonant excitation from CNTs formed by the surface decomposition of SiC. Fine CNTs having diameters between 0.7 and 1.3 nm were observed on SiC after heating at 1700 °C in a vacuum electric furnace. These diameters are considerably smaller than those previously observed for CNTs grown by this technique.

Formation process of nanosized cap structures on a thermally treated 6H-SiC(000-1) substrate was investigated using atomic-resolution ultrahigh-vacuum scanning tunneling microscopy (UHV-STM). After formation of clusters of carobon particles 1-2 nanometer in diameter at 1150°C, these nanoparticles merged, forming nanosized cap structures. Hexagonal carbon networks, partly composed of pentagons, were clearly observed on the surface of the cap structures for a sample annealed above 1200 o C. A model for the formation of carbon nanocaps on 6H-SiC(000-1) was proposed. 0901-Ra11-13-Rb11-13.1 Mater. Res. Soc. Symp. Proc. Vol. 901E