Substrate and Process Interplay During Synthesis of Millimeter Long Multi-Wall Carbon Nanotube Arrays

This paper reports data related to the effects of the substrate design and the deposition parameters on the growth of millimeter long multi-wall carbon nanotube (MWCNT) arrays by CVD (Chemical Vapor Deposition). Iron catalyst was formed on top of multilayered substrates of Si/SiO
2
and Si/SiO
2
/Al
2
O
3
by e-beam evaporation. The CNT synthesis was carried on in a hydrogen/ethylene/water/argon environment at 750 °C for different periods of deposition time. Atomic Force Microscopy (AFM), Environmental Scanning Electron Microscopy (ESEM), High Resolution Transmission Electron Microscopy (HRTEM), and Micro-Raman Spectroscopy were employed to characterize the substrates before and after nanotube growth. The study shows that for specific processing conditions, the length of highly oriented carbon nanotube arrays depends on the annealing temperature of the catalyst which determines the size of the catalyst particle. Other factors affecting the length are: substrate design and size and water concentration. The array nanotubes mitigate the limitations of the powdered “spaghetti type” CNT, and this is expected to open up new applications for them.