A formation mechanism of carbon nanotube films on SiC(0001)

We report a remarkable difference of decomposed structures on the Si(0001) and C(000 (1) over bar) faces of a SiC single crystal observed by using a cross-sectional high-resolution electron microscopy. An aligned carbon nanotube (CNT) film was fabricated on the C face perpendicular to the surface after heating at 1700 degrees C for half an hour in a vacuum. On the contrary, a very thin layer of graphite sheets parallel to the surface was formed on the Si face under the same condition. It is proposed that the growth of CNTs is determined by the generation of nanocaps at the initial stage, by comparing the difference of the decomposition mechanisms on the both faces. (C) 2000 American Institute of Physics. [S0003-6951(00)04330-8].