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Thin film catalyst and substrate interactions on the CCVD (catalytic chemical vapor deposition) growth of carbon nanotubes.

机译：薄膜催化剂和基材在碳纳米管的CCVD（催化化学气相沉积）生长上相互作用。

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摘要

A detailed investigation into the growth of single-walled carbon nanotubes (SWNTs) on thin metallic films deposited on various substrates was performed. In this research, Al/Fe/Mo multi-layer thin films were deposited by electron beam deposition on various substrates to determine which substrates promote the growth of SWNTs over multi-walled nanotubes (MWNTs) during the decomposition of methane gas. The chemical vapor deposition (CVD) parameters such as time (10 minutes), temperature (950°C), and gas type and flow (methane at 0.5 slpm) were kept constant. This research varies from previous research in that thin metallic films are utilized instead of prefabricated nanoparticles or liquid phase catalyst. The use of nanoparticles and liquid catalysts is not a viable solution for the application in modern semiconductor integrated circuit (IC) technology. Both, processes contain problems in reproducibility and uniformity over an entire wafer. The advantage of a thin film deposition process is the ease in fabrication and reproducibility and the ability of the thin films to be incorporated into modern IC technology and processes (patterning and etching). The application of thin films also leads to the possibility of controlling the location of SWNT growth and possibly the direction of SWNT growth. Prefabricated nanoparticles and liquid catalyst are not easily selectively deposited on a substrate at specific sites.; The main difficulty with the implementation of thin film catalysts for the production of SWNTs is the ability to produce adequately sized nanoparticles of Fe during the CVD. Particles need to be less than 5 nm in diameter for the production of SWNTs, which contain diameters between 0.8–5.0 nm. Therefore, the ability to initially form nanosized particles and then disperse the Fe catalyst throughout the substrate is a critical factor in controlling the size of the nanoparticles formed and hence the type of carbon nanotube growth. This ability to form nanoparticles from the evaporated films should be directly related to how the metal layers and the substrate interact.; The previous research has also not tried to understand the direct role of the substrate in influencing SWNT or MWNT growth. Do the substrate characteristics (crystallinity, porosity, stability, chemistry, etc.) influence the growth of SWNTs over MWNTs? This is a major factor in the growth of nanotubes from thin films since the properties of the substrate will directly relate to the formation of nanosized particles. The substrates influence may also lead to the possible selectivity of SWNT growth over MWNT growth.; It was determined in this research that the type of substrate employed as the supporting material for the Fe thin film catalyst has a strong effect on controlling the growth of either SWNTs or MWNTs. There are clear trends noticeable in the growth of either SWNTs or MWNTs on the various substrates. The ideal substrate for SWNT growth is the spun-on alumina film, while, single crystal substrates promote the growth of mixed SWNTs and MWNTs. All remaining substrates grew primarily MWNTs. The actual mechanisms associated with the selectivity of SWNT growth over MWNT growth is difficult to determine due to the many variables and complexities associated with this research.
机译：对沉积在各种基板上的金属薄膜上的单壁碳纳米管（SWNT）的生长进行了详细的研究。在这项研究中，通过电子束沉积在各种基板上沉积Al / Fe / Mo多层薄膜，以确定在甲烷气体分解过程中哪些基板在多壁纳米管（MWNT）上促进了SWNT的生长。化学气相沉积（CVD）参数（例如时间（10分钟），温度（950°C），气体类型和流量（0.5 slpm的甲烷））保持恒定。这项研究与以前的研究不同之处在于，利用金属薄膜代替了预制的纳米颗粒或液相催化剂。对于现代半导体集成电路（IC）技术的应用，使用纳米颗粒和液体催化剂不是可行的解决方案。两种工艺都在整个晶片上都存在再现性和均匀性的问题。薄膜沉积工艺的优势在于易于制造和可重复性，以及将薄膜整合到现代IC技术和工艺（构图和蚀刻）中的能力。薄膜的应用还导致控制SWNT生长的位置以及SWNT生长方向的可能性。预制的纳米颗粒和液体催化剂不容易选择性地沉积在基材上的特定位置。实施用于生产SWNT的薄膜催化剂的主要困难是在CVD过程中产生足够尺寸的Fe纳米颗粒的能力。为了生产单壁碳纳米管，颗粒的直径必须小于5 nm，其直径在0.8- <5.0 nm之间。因此，最初形成纳米级颗粒然后将Fe催化剂分散到整个基材中的能力是控制所形成的纳米颗粒的尺寸以及碳纳米管生长类型的关键因素。由蒸发的膜形成纳米颗粒的能力应与金属层和基材如何相互作用直接相关。先前的研究也没有试图了解底物在影响SWNT或MWNT生长中的直接作用。基材特性（结晶度，孔隙率，稳定性，化学性质等）是否会影响SWNT相对于MWNT的生长？这是从薄膜中生长纳米管的主要因素，因为基材的性能将直接与纳米颗粒的形成有关。底物的影响也可能导致SWNT生长相对于MWNT生长的选择性。在这项研究中确定，用作Fe薄膜催化剂载体材料的基质类型对控制SWNTs或MWNTs的生长具有强烈的影响。在各种基质上，SWNT或MWNT的增长都有明显的趋势。 SWNT生长的理想衬底是旋转氧化铝膜，而单晶衬底则促进了混合SWNT和MWNT的生长。所有剩余的底物主要生长MWNT。由于与本研究相关的许多变量和复杂性，很难确定与SWNT生长相对于MWNT生长的选择性相关的实际机制。

著录项

  • 作者

    Ward, Jonathan Wesley.;

  • 作者单位

    Rensselaer Polytechnic Institute.;

  • 授予单位 Rensselaer Polytechnic Institute.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 204 p.
  • 总页数 204
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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