A GISAXS study of the angular dependence of carbon nanotubes grown on a plain substrate by the dc HF CCVD process

摘要

We report on a quantitative Grazing Incidence Small Angle X-ray Scattering (GISAXS) study of the angular dependence of oriented carbon nanotubes (CNTs) grown by a catalytically activated, plasma direct current or plasma enhanced and hot filaments-assisted catalytic chemical vapour deposition (dc HF CCVD or PE HF CCVD) process. To synthesize these CNTs, some transition metal (TM) particles were used as a catalyst and dispersed on plain SiO_2 (thickness 5 nm)/Si(100) substrates prior to the growth of CNTs. Some morphological (diameter, height) and disorder parameters have been determined using the GISAXS technique in the framework of Effective Layer Born Approximation (ELBA) and Distorted-Wave Born Approximation (DWBA) on noncorrelated multilayer systems. The GISAXS patterns, although dominated by envelope features of disordered islands, provide important complementary quantitative information about CNT films. The results are compared to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. Furthermore, the GISAXS patterns could only be acceptably reproduced by considering an inter-mixing C-Co contribution and the metallic cobalt let on top of the CNT. While monitoring the incidence angle, we found that the disorder parameter decreases with increasing incidence angle, showing that the in-plane system order increases from the surface to the inner layers.