AVS 53rd International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2+TF-WeM

Paper PS2+TF-WeM12
Analyses of CH4/H2 RF Plasma and Iron Catalysts for Control of Carbon Nanotube Growth

Wednesday, November 15, 2006, 11:40 am, Room 2011

Session: Plasma Deposition
Presenter: Y. Suda, Hokkaido University, Japan
Authors: A. Okita, Hokkaido University, Japan
Y. Suda, Hokkaido University, Japan
A. Ozeki, Hokkaido University, Japan
A. Oda, Nagoya Institute of Technology, Japan
J. Nakamura, Tsukuba University, Japan
K. Bhattacharyya, Hokkaido University, Japan
H. Sugawara, Hokkaido University, Japan
Y. Sakai, Hokkaido University, Japan
Correspondent: Click to Email
We have studied CH@sub 4@/H@sub 2@ gas mixture RF plasma by one-dimensional fluid modeling and iron catalysts by X-ray photoelectron spectroscopy (XPS) for controlling carbon nanotube (CNT) growth in plasma-enhanced CVD (PECVD).@footnote 1,2@ To control CNT growth in terms of length, diameter, number density and orientation, understanding the behavior of hydrocarbon (C@sub x@H@sub y@) radicals and ions onto metal-catalyzed substrate becomes important. So far, we have shown that the carbon amount evaluated from the fluxes of C@sub x@H@sub y@ radicals and ions by the modeling is reasonably consistent with that in CNTs grown by PECVD.@footnote 1@ The PECVD setup sustains the CH@sub 4@/H@sub 2@ or H@sub 2@ plasma in a pressure range of 1-10 Torr. The substrate temperature is kept at 550°C for reduction and 650°C for growth. Length, diameter and number density of the CNTs grown are analyzed. The carbon atom density in a graphene sheet (3.81X10@super 15@ atoms/cm@super 2@) is used to evaluate the amount of carbon in CNTs. One-dimensional fluid modeling analyzes the densities and fluxes of C@sub x@H@sub y@ radicals and ions between powered and grounded electrodes. Assuming the sticking probability of C@sub x@H@sub y@ radicals on substrate: CH, 0.025; CH@sub 2@, 0.025; CH@sub 3@, 0.01; C@sub 2@H@sub 5@, 0.01; H, 0.01,@footnote 3@, we predict the amount of carbon which are supplied from the plasma and incorporated into CNTs. Very recently, we have shown that the content of iron oxide in the catalyst analyzed by XPS correlates with CNT growth.@footnote 2@ In this presentation, we discuss the growth speed of CNTs by both the PECVD and modeling and the CNT growth duration by XPS analysis. @FootnoteText@@footnote 1@A. Okita, et al., J. Appl. Phys., 99 (2006) 014302 @footnote 2@A. Okita, et al, Jpn. J. Appl. Phys. (accepted) @footnote 3@I. B. Denysenko, et al., J. Appl. Phys. 95, 2713 (2004).