Structural characteristics of carbon nanorods and nanotubes grown using electron cyclotron resonance chemical vapor deposition

Abstract

Different types of carbonaceous materials were synthesized by electron cyclotron resonance chemical vapor deposition on Ni-coated glass substrates with radio-frequency (rf) self-biasing using a gas mixture of CH4 and Ar. Vertically aligned carbon nanorods and multiwalled carbon nanotubes (MWNTs) were obtained at the rf bias voltages of −100 and −200 V, respectively. High-resolution transmission electron microscopy indicated that the distance between two graphene layers of carbon nanorods is much larger than that of well-graphitized MWNTs having a typical value of graphite. Structural characteristics of carbon nanorods and well-graphitized MWNTs were investigated by electron-energy-loss spectra, in which the energy of π+σ plasmon peak obtained from carbon nanorods shifts to a lower value of 23.8 eV, compared to 25.5 eV from well-graphitized MWNT. Low-energy loss plasmon due to π electrons at 6 eV was not observed in carbon nanorods, but clearly defined for well-graphitized MWNTs. In addition, x-ray photoelectron spectroscopy showed that the delocalization of π electrons becomes more pronounced as the structure of carbonaceous films evolves into more crystalline phase from carbon nanowalls to well-graphitized MWNTs with increasing rf bias voltages. These results can suggest that ionic bombardment energy at high rf bias voltages provides sufficient internal energy for dehydrogenation from hydrocarbon molecules, and thus well-graphitized MWNTs can be synthesized even at low temperatures.

Synthesis of C60 nanotubes by liquid–liquid interfacial precipitation method: Influence of solvent ratio, growth temperature, and light illumination

“…nanotubes [1,2], nanorods [3,4], nanofibers [5,6], nanowires [7,8], nanohorns [9,10], with promising physical and chemical properties, have been fabricated. In this paper, fullerene "nanotubes" refer to single crystalline thin whiskers, composed of densely packed fullerene molecules along their growth axis discovered by Miyazawa et al in 2005 [11].…”

Chemical vapour infiltration of nano‐structured carbon in porous silicon

“…1 bottom), such sp² carbon material was clearly nanostructured. At this stage, the real nature of this nanosructured carbon cannot be confirmed by the Raman spectra that are compatible with different carbon species, for example multiwalls nanotubes (MWNTs) or carbon nanorods [10,11]. Additional work is in progress, including TEM investigations, to clarify this point.…”

Bias-independent growth of carbon nanowalls by microwave electron-cyclotron resonance plasma CVD

“…Since plasma generation mechanism is of electrode-less nature, ECR plasma deposition results in very low contamination compared with other plasma processes. In spite of having these advantages, there are very few reports available on the successful deposition of CNWs by ECR plasma CVD [9,10,17]. The main difference between these synthesis routes and the one presented here is that no external substrate bias was applied during growth process.…”

“…CNW was first discovered by Wu et al [1] during the growth experiment of carbon nanotubes (CNTs) by microwave plasma-enhanced chemical vapour deposition (MPECVD) [1]. Since its discovery in 2002, CNWs have been prepared by various methods, including MPECVD [1][2][3], radio-frequency plasma-enhanced chemical vapour deposition [4], DC plasma-enhanced chemical vapour deposition [5,6], hot-wire chemical vapour deposition [7,8] and electron-cyclotron resonance chemical vapour deposition (ECR-CVD) [9,10].…”