High-Resolution Laser Diagnostics and Modeling of Single-Walled Carbon Nanotube Synthesis by Plasma-Enhanced CVD

CBET-0828165 Lucht本研究旨在开发通过等离子体增强化学气相沉积（PECVD）控制合成单壁碳纳米管（SWCNTs）的关键科学。 碳纳米管已被证明产生广泛的杰出的物理性能，具有重要的技术和社会意义。然而，一些关键的性能强烈地依赖于材料参数，到目前为止，在合成过程中基本上是不可控的。碳纳米管的良好控制制造可以在广泛的应用中实现突破，包括超快场效应晶体管和纳米电子电路，直接能量转换过程，场发射器件，高温超导体，纺织纤维和高导热性薄膜。此外，微波等离子体具有潜在的非常高浓度的物质，如CH 3和C原子。这些物种在燃烧化学中非常重要，但这些物种的诊断技术还没有得到很好的发展。因此，H2/CH 4等离子体作为开发新的光学诊断技术的试验平台具有极大的意义。研究团队开创的一项技术通过减少生长表面的原子氢浓度来辅助合成，即使在室温下也能蚀刻SWCNT。关键是施加一个正的电偏压的生长表面排斥H+离子it. Although原子H的作用似乎是至关重要的，在这些新的过程中，很少有人知道的等离子体的成分附近的生长表面。空间分辨的光学测量和补充模型，应用和开发在这项工作中，是至关重要的理解的物种，如原子氢和含碳的前体碳纳米管合成的作用。在这项工作中获得的知识，预计将使合成协议和模型，反过来将有助于控制CNT材料，结构和设备的合成的长期目标的创建。该计划将通过与电气工程师，材料科学家，物理学家和化学家的现有合作，使机械工程研究生接触到科学和工程的其他领域，如分子电子学和等离子体物理学。此外，纳米技术和激光诊断方面令人兴奋的新研究将通过参加普渡大学夏季本科生研究奖学金（SURF）计划，强烈吸引国内学生进入科学和技术研究职业。

CBET-0828165LuchtThis research aims to develop key science for developing controlled synthesis of single-wall carbon nanotubes (SWCNTs) by plasma-enhanced chemical vapor deposition (PECVD). Carbon nanotubes have been shown to produce a wide range of outstanding physical properties with important technical and societal implications. However, some crucial properties depend strongly on material parameters that, to date, have been largely uncontrollable in the synthesis process. Well controlled fabrication of carbon nanotubes could enable breakthroughs across a vast range of applications, including ultrafast field-effect transistors and nanoelectronic circuits, direct energy-conversion processes, field-emission devices, high-temperature superconductors, textile fibers, and high-thermal-conductivity films. In addition, the microwave plasma has potentially very high concentrations of species such as CH3 and C-atom. These species are very important in combustion chemistry, but diagnostic techniques for these species are not well developed. The H2/CH4 plasma is thus of great interest as a testbed for the development of new optical diagnostic techniques.A technique pioneered by the research team aids synthesis by reducing concentration of atomic hydrogen from the growth surface, where they etch SWCNTs even at room temperature. The key is applying a positive electrical bias to the growth surface to repel H+ ions from it. Although the role of atomic H appears to be critical in these new processes, very little is known about the composition of the plasma near the growth surface. Spatially resolved optical measurements and complementary models, to be applied and developed in this work, are critical to understanding the role of species such as atomic H and carbon-containing precursors to CNT synthesis. The knowledge gained in this work is expected to enable the creation of synthesis protocols and models that in turn will aid the longer-term goal of controlled synthesis of CNT materials, structures, and devices. The proposed program will expose mechanical engineering graduate students to additional areas of science and engineering, such as molecular electronics and plasma physics, through existing collaborations with electrical engineers, material scientists, physicists, and chemists. In addition, exciting new research on nanotechnology and laser diagnostics will strongly attract domestic students into science and technology research careers through participation in Purdue's Summer Undergraduate Research Fellowship (SURF) program.