Growth of Carbon Nanotubes by PECVD

Carbon nanotubes were grown from acetylene and hydrogen gas mixture directly on stainless steel plates by powered PECVD and then electric double layer capacitors were fabricated from them without any further treatment. It was found that suitable pretreatment of metal substrate was required for the satisfactory growth of carbon nanotubes. In this study substrates were polished, etched in HF solution and then treated with hydrogen plasma before the growth of carbon nanotubes. SEM shows that the surface of substrate became smooth after polishing. But it was severely etched to reveal grains after dipping in HF solution. With hydrogen plasma treatment the grains become more spherically shaped and grew in size. When the size of grains was of tens of nanometers carbon nanotubes were grown. But exposing substrates to hydrogen plasma for 10 minutes or longer caused grains to grow larger than 100 nm and growth of carbon nanotubes became much poorer. Carbon nanotubes grown in this study were multiwalled and not straight in shape. Capacitors made from carbon nanotubes showed initial capacitance in the range of 80 - 100 F/g.