抄録
This paper presents pressure-dependent (5 kPa-100 kPa) selective growth of multi-walled and single-walled carbon nanotubes (CNTs) in plasma enhanced chemical vapor deposition (PECVD). High-purity, vertically-aligned single-walled CNTs (SWCNTs) were synthesized only when PECVD was employed at atmospheric pressure, while multi-walled CNTs were preferentially synthesized when the total pressure was lower than 20 kPa. In the reduced pressure range, catalyst coagulation was unavoidable at the initial stage of CNT nucleation: catalyst coagulation took place independently of plasma-induced damage such as excess supply of reactive species and energetic ion bombardment. If catalyst coagulation was avoided at the moment of CNT nucleation by marker growth technique, SWCNTs were grown in the root growth regime even at 5 kPa; however, top SWCNT layer, which is adjacent to the reactive plasma, was seriously contaminated by amorphous carbon produced as a result of excess supply of reactive species.
