Growth of metal-free carbon nanotubes with amorphous carbon catalyst layer on glass substrates by microwave plasma enhanced chemical vapor deposition

We have investigated growth of metal-free carbon nanotubes (CNTs) on glass substrates with a microwave plasma enhanced chemical vapor deposition (MPECVD) method. An amorphous carbon (a-C) film was used as a catalyst layer to grow metal-free CNTs. The a-C films were deposited with a RF magnetron sputtering method using carbon target at room temperature on glass substrates. The CNTs were prepared using a microwave plasma-enhanced chemical vapor deposition (MPECVD) method by using methane (CH₄) and hydrogen (H₂) gas. We have pretreated a-C catalyst layer using H₂ plasma at 700°C and the CNTs were grown at different temperatures (350°C, 450°C and 550°C) and other conditions were fixed. The growth trends of CNTs against temperature were observed by field emission scanning electron microscopy (FE-SEM).