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Well-aligned carbon nanofibers synthesized by electron cyclotron resonance chemical vapor deposition Fumiyuki Hoshi a, Kazuo Tsugawa a, Akiko Goto a, Takefumi Ishikura a, Satoshi Yamashitab, Motoo Yumura a,d, Takashi Hirao c Shuzou Fujiwara d and Yoshinori Koga a,d a FCT Research Laboratory, JFCC, c/o NIMC, Japan b Frontier Technology Laboratory, Tokyo Gas CO., LTD, Japan c Department of Electric Engineering, Osaka University, Japan d Department of Advanced Chemical Technology, NIMC, Japan Abstract Aligned carbon nanofibers and hollow carbon nanofibers were grown by MW ECR-CVD method using methane and argon mixture gas at the temperature of 550℃. Carbon nanofibers and hollow carbon nanofibers were deposited perpendicularly on Si substrate and on Si substrate coated with Ni catalyst, respectively. Raman spectra of aligned carbon nanofibers and hollow carbon nanofibers showed new bands of 1340 and 1612 cm-1 of the first-order Raman scattering and 2660, 2940 and 3220 cm-1 of the second-order Raman scattering. The second-order Raman scattering bands were assigned to two overtone and one combination bands on the basis of a similar assignment of micro crystal graphite. Combination bands are intense unusually. Field emitter characteristics of the well-aligned carbon nanofibers and hollow carbon nanofibers were investigated and the current densities were 7.25 mA/cm2 and 0.69 mA/cm2 at 12.5 V/µm, respectively. Introduction Selective positioning and growth of carbon nanofiber or carbon nanotube is important for future integration micro devices. Especially, perpendicular alignment has been an important factor due to technological importance for applications such as field emission flat panel display. Field emitter from carbon fibers in 7∼8µ m in diameter have researched and was a problem of reproducibility [4]. Since nanotubes as an excellent electron emission source have discovered by Iijima [5], high density current from nanometric tips have been reported by many researchers [6]. Raman bands of carbon materials have been reported by many researchers. [1-3] Raman spectra of carbon fibers synthesized higher than 1100℃ have been researched by Endo and Dresselhaus. [3] The diameter of these carbon fibers were more than 80 nm with sub micron and micron order of fibers. They reported sample exhibited mainly two bands at about 1580 and 1335 cm-1 with a small shoulder appeared at ∼1620 cm-1 after the heat treatment at 1500℃. In this work we report the synthesis of aligned carbon nanofiber, and hollow carbon nanofiber at low temperature of 550 ℃ by ECR(Electron Cyclotron Resonance) -CVD(Chemical Vapor Deposition) method and observed its structure and those of Raman A6.2.1

spectra, electron emission properties.

Gas inlet Microwave 2.45 GHz

CH4 , H2, Ar

Experimental procedure The films were deposited on Magnet coil n-type Si(100) substrates by ECR-CVD system. In Fig.1 the system is equipped with two cylindrical magnets (1T in maximum) at the upper side and a magnet (35mT in maximum) at the Plasma to vacuum pump lower side. The appl