Controlling of deposition time as an effective parameter on purified growth CNTs based on TCVD method

Abstract

According to the unique properties of Carbon nanotubes (CNTs), they have been under scientific investigation for more than fifteen years in different applications. Here we reported the effect of temperature on camphor in a wide range of 500–1150 ˚C. The results indicate that camphor did not decompose below 500 ˚C but very short-length tubes emerged from the silicon substrate at 550 ˚C which is suggesting that the catalyst activity. According to the results, the CNT growth rate was abruptly increased at 600 ˚C. This process was done on the same condition by optimizing the temperature up to 900 ˚C. FESEM images indicate the highest catalyst activity at 850 ˚C which direct the experiment to grow purified CNT up to 3 µm in the length. This result suggests that, at low temperatures, the catalyst–support interaction is strong enough not to let the metal particles to involve in deposition process, but at 850 ˚C MWCNTs and SWCNTs can be selectively grown as a function of CVD temperature. The optimum deposition time was found in 30 minutes, which based on the Raman shift results the growth CNTs has shown high purity and crystallinity as well as high aspect ratio.