Deposition of vertically oriented carbon nanofibers in atmospheric pressure radio frequency discharge

Journal Article · Sun Jan 15 00:00:00 EST 2006 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2163997· OSTI ID:20787801

Nozaki, Tomohiro; Goto, Tomoya; Okazaki, Ken; Ohnishi, Kuma; Mangolini, Lorenzo; Heberlein, Joachim; Kortshagen, Uwe ^[1]

---

1. Department of Mechanical and Control Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro Tokyo 1528552 (Japan)

Deposition of vertically oriented carbon nanofibers (CNFs) has been studied in an atmospheric pressure radio frequency discharge without dielectric barrier covering the metallic electrodes. When the frequency is sufficiently high so that ions reside in the gap for more than one rf cycle ('trapped ions'), the operating voltage decreases remarkably and the transition from a uniform glow discharge to an arc discharge is suppressed even without dielectric barriers. More importantly, the trapped ions are able to build up a cathodic ion sheath. A large potential drop is created in the sheath between the bulk plasma and the electrode, which is essential for aligning growing CNFs. At the same time, the damage to CNFs due to ion bombardment can be minimized at atmospheric pressure. The primary interest of the present work is in identifying the cathodic ion sheath and investigating how it influences the alignment of growing CNFs in atmospheric pressure plasma-enhanced chemical-vapor deposition. Spectral emission profiles of He (706 nm), H{alpha} (656 nm), and CH (432 nm) clearly showed that a dark space is formed between the cathode layer and the heated bottom electrode. However, increasing the rf power induced the transition to a nonuniform {gamma}-mode discharge which creates intense plasma spots in the dark space. Aligned CNFs can be grown at moderate input power during the initial stage of the deposition process. Catalyst particles were heavily contaminated by precipitated carbon in less than 5 min. Alignment deteriorates as CNFs grow and deposition was virtually terminated by the deactivation of catalyst particles.

• OSTI ID: 20787801
• Journal Information: Journal of Applied Physics, Vol. 99, Issue 2; Other Information: DOI: 10.1063/1.2163997; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERIC PRESSURE
CARBON
CARBON FIBERS
CATALYSTS
CATHODES
CHEMICAL VAPOR DEPOSITION
DEACTIVATION
DIELECTRIC MATERIALS
ELECTRIC ARCS
GLOW DISCHARGES
ION BEAMS
IONS
LAYERS
NANOSTRUCTURES
PLASMA
PLASMA SHEATH
PRECIPITATION
RADIOWAVE RADIATION
TRAPPING