Effect of Gas Pressure on the Density of Horizontally Aligned Single-Walled Carbon Nanotubes Grown on Quartz Substrates

We investigate the influence of gas pressure on the growth of horizontally aligned single-walled carbon nanotubes (SWCNTs) on R-cut and r-cut crystal quartz substrates by alcohol catalytic chemical vapor deposition (CVD). The density of horizontally aligned SWCNTs was found to depend highly on gas pressure. A study of the SWCNT growth as a function of CVD time revealed that the density of horizontally aligned SWCNTs continued to increase for 10 min at reduced pressure, whereas the density saturated rapidly at higher pressure even though catalysts were not deactivated. We argue that variation of incubation time for low-pressure CVD is key for independent growth of horizontally aligned SWCNTs and hence higher density growth.