Growth and Characterization of Nanostructured Carbon Film Field Emitters

本项目旨在生长和表征由碳纳米管和非晶态碳膜组成的纳米结构碳膜。薄膜将通过CVD(化学气相沉积)生长。利用原子分辨率超高真空(UHV)扫描隧道显微镜(STM)、拉曼光谱、俄歇光谱、紫外光电子能谱和X射线光电子能谱研究薄膜的结构和电子性质随生长条件的变化。还将测量场发射的开启场强、发射点密度、电子能量分布以及场发射电流的稳定性和寿命。将详细研究残余气体对FE性能的影响。对于碳纳米管和非晶态碳膜，将分别针对平板显示器的应用评估导致最佳管密度和粗糙度密度的生长条件。这种薄膜具有潜在的技术应用，如平板显示器(FPD)中的冷阴极电子发射器、微型微波源、高度准直的电子源和真空微电子。利用超高压扫描隧道显微镜，研究了吸附物对单个碳纳米管帽的结构和电子性质的影响。超高真空扫描隧道显微镜还将被用来研究在金刚石中引起负电子亲和力的吸附物的结构和电子性质，如氢、钛和铯。将碳纳米管和非晶态碳膜的有限元特性与金刚石膜和金刚石包覆的钼微尖的有限元特性进行比较，以确定用于有限元分析的最佳材料。%该项目解决了材料科学中具有高技术相关性的专题领域的基础研究问题。先进的表征技术可以更好地理解和控制基本过程，这将促进基础材料科学和技术的进步。从研究中获得的基本知识和理解有望有助于平板显示以及电子和光子材料的相关应用。该方案的一个重要特点是，通过在一个具有根本意义和技术意义的领域对学生进行培训，将研究和教育结合起来。

This project aims to grow and characterize nanostructured carbon films consisting of carbon nanotube and amorphous carbon films. Films will be grown by CVD (chemical vapor deposition). Structural and electronic properties will be studied as a function of growth conditions using atomic resolution ultra-high vacuum (UHV) scanning tunneling microscopy (STM), Raman spectroscopy, Auger spectroscopy, ultraviolet photoemission spectroscopy and x-ray photoemission spectroscopy. The turn-on field for field emission (FE), emission site density, electron energy distribution, and stability and lifetime of the FE current will also be measured. Effects of residual gases on FE properties will be studied in detail. For carbon nanotube and amorphous carbon films, growth conditions resulting in optimum tube and asperity density, respectively, will be assessed for FPD applications. Such films have potential techno-logical applications as cold cathode electron emitters in flat panel displays (FPDs), miniature micro-wave sources, highly collimated electron sources and vacuum microelectronics. Using UHV STM, the effects of adsorbates on the structural and electronic properties of the caps of individual carbon nano-tubes will be studied. UHV STM will also be used to study structural and electronic properties of ad-sorbates that induce negative electron affinity in diamond such as hydrogen, Ti and Cs. The FE proper-ties of carbon nanotube and amorphous carbon films will be compared with those of diamond films and diamond-coated Mo microtips to determine the best material for FE applications. %%%The project addresses basic research issues in a topical area of materials science with high technologi-cal relevance. Advanced characterization techniques allow greater understanding and control of ele-mentary processes which will allow advances in fundamental materials science and technology. The basic knowledge and understanding gained from the research is expected to contribute to flat panel dis-play, and related applications of electronic and photonic materials. An important feature of the pro-gram is the integration of research and education through the training of students in a fundamentally and technologically significant area.***