標題: Comparisons on properties and growth mechanisms of carbon nanotubes fabricated by high-pressure and low-pressure plasma-enhanced chemical vapor deposition
作者: Lin, CH
Lee, SH
Hsu, CM
Kuo, CT
材料科學與工程學系
Department of Materials Science and Engineering
關鍵字: carbon nanotubes;microwave plasma CVD;electron cyclotron resonance CVD;field emission;growth mechanism
公開日期: 1-Nov-2004
摘要: Effects of plasma pressure and the presence of nitrogen on growth of carbon nanotubes (CNTs) and their properties were studied by using microwave plasma chemical vapor deposition (MPCVD) (pressure=600-3300 Pa) and electron cyclotron resonance chemical vapor deposition (ECR-CVD) (pressure=0.3-0.6 Pa) systems. CH4/H-2 and CH4/N-2 were used as source gases, and Co as the catalyst. The structures and properties of CNTs were characterized by using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectra, and field emission I-V measurements. The results show that. CNTs made by higher plasma pressure system have a higher growth rate (typically 1-3 mum/min), smaller tube diameter, better field emission properties, and better tube quality. The growth rate is related to the availability of carbon source. The morphology change from spaghetti-like to well-aligned CNTs is discussed in terms of directed ions. The change in field emission properties is reasoned in terms of geometric enhancement factor and screening effect for different tube morphologies. The presence of nitrogen plasma can have the following effects: increasing tube diameter, increasing straightness of CNTs, forming of bamboo-like CNTs, deterioration of field emission properties, and shifting of Raman peak toward lower-frequency side (or increasing residual tensile stress). (C) 2004 Elsevier B.V. All rigths reserved.
URI: http://dx.doi.org/10.1016/j.diamond.2004.06.033
http://hdl.handle.net/11536/25717
ISSN: 0925-9635
DOI: 10.1016/j.diamond.2004.06.033
期刊: DIAMOND AND RELATED MATERIALS
Volume: 13
Issue: 11-12
起始頁: 2147
結束頁: 2151
Appears in Collections:Conferences Paper


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