Influence of heating rate upon the growth of carbon nanotubes by the SiC surface decomposition method

Abstract

The effect of heating rate upon the formation of carbon nanotubes (CNTs) on a SiC(000 1̄) surface was investigated. The samples were heated to 1700°C at a heating rate of 100–400°C min−1 in the ultrahigh vacuum (<1.0×10−8 Pa) or low vacuum (1.0×10−2 Pa) chamber and held at temperature for 1 h. Sample cross sections were observed using transmission electron microscopy (TEM) with a 300 kV electron beam. When using a slow heating rate, CNTs are observed on the SiC(000 1̄) surface. However, when the heating rate exceeds 400°C min−1, an amorphous layer is formed on the interface between the CNT layer and the SiC substrate. It is thought that excess carbon atoms are decomposed and cannot form CNTs, but instead form an amorphous layer at the interface.