Studies On The CVD Growth Of Carbon Nanotubes On Silicon/Silica Substrates

Carbon nanotubes have novel mechanical, electrical properties, and they are typical 1D quantum wire. They are expected to be the fundamental materials for future micro- or nano- electronic devices. The prerequisite of the manufacrue of microelcectronic devices from carbon nanotubes is the orderly growth of carbon nanotubes on silicon or silica substrates. That is also the necessities of the compatibility of carbon nanotubes growth processes and silicon processes. Therefore, the investigation of this paper focused on the basic topic of growth of carbon nanotubes on silion wafer substrates, and extended to the discussion of feasibility of forming micro- or nano- electronic devices.First, direct growth of carbon nanotubes array are prepared vetically to the silicon substrate. Xylene is used as carbon source precursor and ferrocene as catalyst, argon and hydrogen as carrier gases. The as-grown carbon nanotubes have homogeneous diameters, good crystallization and orientation.Second, catalyst prepared by conventional method is spin-coated to form liquid catalyst film on the surface of silicon substrates. The single-walled nanotubes are prepared on the substrate; however, there is a great amount of residual catalyst carrier (Al₂O₃), which is the main obstale of manufacture of microelectronic devices based on carbon nanotubes.Third, silicon wafer are etched by electrochemical method to make porous silicon as the substrates of carbon nanotube growth. Compared with polished silicon surface, porous silicon layer is helpful for the formation of homegenous distributed nano-sized catalyst particles. Since the process of porous silicon is compatible to silicon processes, the method can be used to manufacture real devices.