Position Controlled Growth in Carbon Nanotubes Catalyzed by an Iron Nano-dot Array
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0900-O09-03.1
Position controlled growth in carbon nanotubes catalyzed by an iron nano-dot array Jun-ichi Fujita,1, 2 Takahito Mukawa,1, 2 Satoshi Okada,1, 2 Ryota Kobayashi,1, 2 Masahiko Ishida,1, 3 Toshinari Ichihashi,1, 3 Yukinori Ochiai,1, 3 and Shinji Matsui1, 4 1
CREST JST, 4-1-8, Hon-cho, Kawaguchi, Saitama, 332-0012, Japan Institute of Applied Physics, University of Tsukuba, Tennodai, Tsukuba, 305-8573, Japan 3 Fundamental Res. Labs., NEC Corporation, 34 Miyukigaoka, Tsukuba, 305-8501, Japan 4 University of Hyogo, LASTI, 3-1-2 Koto, Kamigori, Ako, Hyogo, 678-1205, Japan 2
ABSTRACT We report a successful demonstration of a position control technique for carbon nanotube growth catalyzed by an iron nano-dot array, which was fabricated by using electron beam induced chemical vapor deposition (EB-CVD). Point irradiation of an electron beam with ferrocene source gas produced an amorphous carbon dot containing iron atoms uniformly dispersed into the dot, and its position could be precisely controlled. Vacuum annealing of the ferrocene based dot induced segregation of iron nano-particles, whose size was almost proportional to the beam irradiation time. After removing the carbon residue, an ethanol CVD process carried out at 800 ºC under 6.5x103 Pa of ethanol vapor induced carbon nanotube growth from the dots. Many grown nanotubes were very thin having 0.7 to 1.8 nm in diameter, which was much smaller than that of the bottom iron particle. INTRODUCTION Key issue to control position and thickness in carbon nanotube[1] would result in a technique how to manage a single iron nanoparticle within the truly nano-scale accuracy. One of major approaching way was to use a lithographically patterned metal films[2] so as to catalyze nanotube growth at certain position, however, the size reduction of the catalyst strongly restricted by the lithographical resolution, and it would be in about 10 nm even if one would utilized an electron beam writing system. In addition, such metal films produced multiple iron particles dispersed around the original pattern area, which consequently produced a bush of nanotube. Other promising method is to use an iron contained carrier material to restrict the size and position, such as an organic-iron-containing patterned resist[3] and iron stored protein[4], where the final iron particles were produced by vacuum annealing of the carrier material following by carbon removing process. In contrast, we recently found an interesting phenomenon relating in segregation of iron nanoparticles[5,6], which was observed in a amorphous carbon matrix at about 600 ºC, and a single iron particles was produced in the matrix. Ferrocene
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(C5H5)2Fe) based EB-CVD[7,8] produced a amorphous carbon containing iron atoms uniformly dispersed in the carbon matrix. The amorphous carbon matrix typically formed a dot shape structure having about 30 nm to 60 nm in diameter, and the height was proportional to the beam irradiation time. Thus a short period of beam irradiation produced a very thin dot, and extre
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