| AVS 54th International Symposium | |
| Thin Film | Tuesday Sessions |
| Session TF-TuM |
| Session: | Two-Dimensional Carbon Nanostructures |
| Presenter: | S. Kondo, Nagoya University, Japan |
| Authors: | S. Kondo, Nagoya University, Japan K. Yamakawa, Katagiri Engineering Co., Ltd., Japan M. Hiramatsu, Meijo University, Japan M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
Carbon nanostructures, such as fullerene, carbon nanotubes and carbon nanowalls (CNWs) have received great attention for several applications, due to their outstanding physical, chemical and mechanical properties. Among a variety of nanocarbons, CNWs are considered as two-dimensional carbon nanostructures. CNWs are the graphite nanostructure with edges, which comprise the stacks of plane graphene sheets standing almost vertically on the substrate, forming a unique nanostructure similar to a maze with high aspect ratio. The large surface area and sharp edges of CNWs are useful as templates for the fabrication of other types of nanostructured materials, which have potential various applications such as in energy storage and electrodes for fuel cell as well as an electron field emitter. We have successfully synthesized CNWs using the radical injection plasma enhanced chemical vapor deposition (RI-PECVD) employing C2F6 and H2 gases. The system consists of a parallel-plate capacitively coupled plasma (CCP) region and a surface wave microwave excited H2 plasma (H2-SWP) region over the CCP. Using this system, the heated substrate was showered with fluorocarbon radicals as well as plenty of H atoms in a controlled manner. Considering the practical applications of CNWs, further investigations are required to clarify the growth mechanism and to control their structures and properties. Furthermore, it would be useful to investigate the etching characteristics of CNWs for the modification of CNWs structure or pattern transfer of CNWs to other materials. CNWs were evaluated by Raman spectroscopy, TEM, ellipsometry and XPS measurements. In the initial stage of CNWs growth on a Si substrate by RI-PECVD, we have confirmed that a thin layer of approximately 10 nm in thickness was deposited in the first 1 min, and subsequently CNWs grew in the vertical direction from a lot of nuclei on this thin film. This thin film was found to be amorphous carbon with a little amount of fluorine. The CNWs film with the bottom amorphous carbon layer was exfoliated from the Si substrate. Both sides of the detached CNWs film were etched by Ar/H2 plasma. The etching rates of CNWs and amorphous carbon thin film were 140 and 15 nm/min, respectively. It is noted that after the removal of amorphous carbon thin film, the morphology of the CNWs was still maintained on the backside, resulting in the formation of free-standing CNWs filter or membrane.