Synthesis of carbon nanotubes by microwave plasma-enhanced hot filament chemical vapor deposition

A combined system of microwave plasma-enhanced chemical vapor deposition (MPECVD) and hot filament CVD (HFCVD) has been developed for the growth of various carbon nanotubes, where the source gas (methane) can be decomposed independently through microwave plasma and hot tungsten filament. It is found that microwave plasma provides more efficiently carbon sources for the growth of carbon nanotubes (CNTs). By the help of microwave plasma, long CNTs array with length of 0.3 mm and high-density single-walled carbon nanotubes (SWNTs) have been grown by thermal CVD and hot filament CVD, respectively. Raman spectra of the SWNTs reveal high crystalline as well as narrow diameter distribution.