CAREER: Synthesis and Electronic/Electrical Properties of Carbon Nanotube Junctions

技术本职业项目旨在大幅加强纳米级电子材料领域的研究和教育。研究重点是研究、鉴定和理解新型功能材料——y形碳纳米管结（y -结）的合成和电子特性的基本机理。在六边形碳网中引入五角形、七角形和八角形等拓扑缺陷，将具有不同结构和电子特性的三块纳米管融合在一起，形成y型结。通过这种方法，在单个纳米管分子中寻找金属-金属、金属-半导体和半导体-半导体结。目标是通过回答一系列关键问题来阐明合成机制，包括：y结是通过将一个纳米管分裂成两个还是通过将两个单独的纳米管合并成一个来生长的？什么是生长热力学？拓扑缺陷的类型和三个分支的手性（螺旋度）之间的关系是什么？y型结的纳米结构如何影响其电子/电学性能？该方法包括：1)采用化学气相沉积技术合成y型结；2)结合扫描探针显微镜和透射电镜对纳米结构进行详细研究，揭示其生长机理；3)通过扫描探针显微镜和电输运测量研究电子/电学性质，将电子/电学性质与纳米结构联系起来。所建立的合成、测试和分析方法有望为合理设计功能碳纳米管异质结构和开发碳纳米管基器件做出贡献。更广泛的影响：该项目将为佛罗里达国际大学的学生提供电子材料合成、表征和设计方面的培训。研究生和本科生，特别是妇女和少数民族学生，将被招募并参与拟议的研究项目。学生将接触到最前沿的研究，并参与到快速发展的纳米科学领域的科学发现中。为本科生和研究生开发以纳米科学和纳米技术为重点的先进材料物理课程，通过丰富课堂和实验室的科学教学来提高科学成果。预计这项研究和教育计划将为国际财经大学的学生提供基础知识和独特的技术技能。它还将对目前正在审批最后阶段的物理学博士课程和材料科学与工程博士课程产生重大影响。作为拟议外展计划的重要组成部分，将通过与正在进行的FIU“物理学习中心”（PLC）和为南佛罗里达州高中生服务的“向上发展计划”（UBP）计划合作，为当地高中生组织“纳米材料科学夏令营”。在为期五周的“夏令营”中，学生将通过演讲、互动演示和动手实验体验参与研究课题。科研计划亦会透过讲座，参与向本地社区推广纳米科技，以加深市民对纳米科学和纳米技术的认识。

TechnicalThis CAREER project aims to substantially enhance research and education in the area of nanometer-scale electronic materials. The research emphasis is on studying, identifying and understanding fundamental mechanisms of synthesis and electronic properties of new functional materials - Y-shaped carbon nanotube junctions (Y-junctions). It is anticipated that Y-junctions can be formed by fusing together three pieces of nanotubes with different structure and electronic properties through judicious introduction of topological defects, such as pentagons, heptagons and octagons, into the hexagonal carbon network. In this way metal-metal, metal-semiconductor and semiconductor-semiconductor junctions within individual nanotube molecules are sought. A goal is to elucidate the synthesis mechanism via answering a series of critical questions, including: Are the Yjunctions grown by splitting one nanotube to two or by merging two individual nanotubes to one? What is the growth thermodynamics? What is the relation between the type of topological defects and the chiralities (helicities) of the three branches? How does the nanostructure of Y-junctions affect the electronic/electrical properties? The approach includes: 1) Adapting a chemical vapor deposition technique to synthesize Y-junctions; 2) Detailed studies of nanostructure by a combination of scanning probe microscopy and transmission electron microscopy to reveal the growth mechanism; 3) Investigation of electronic/electrical properties by scanning probe microscopy and electrical transport measurement to relate the electronic/electrical properties to the nanostructures. The methodology established for synthesis, testing and analysis is expected to contribute to rational design of functional carbon nanotube heterostructures and the development of carbon nanotube based devices.Non-TechnicalBroader Impact: The project will provide training for students at FIU (Florida International University) in electronic material synthesis, characterization and design. Graduate and undergraduate students, especially women and minority students, will be recruited and involved in the proposed research projects. Students will be exposed to forefront research and will participate in scientific discovery in the rapidly developing nanoscience field. Advanced materials physics curricula with focus on nanoscience and nanotechnology will be developed for both undergraduate and graduate students to improve science achievement by enriching science teaching in both classroom and laboratories. It is anticipated that this research and education program will provide FIU students with fundamental knowledge and unique technological skills. It will also have substantial impact on the current Ph.D. program in Physics, and on the Ph.D. program in Materials Science and Engineering, currently in the final stages of approval. As an important part of the proposed outreach program, a "Summer Camp of Nanomaterials Science" for local high school students will be organized through collaboration with the on-going FIU "Physics Learning Center" (PLC) and "Upward Bound program" (UBP) programs serving high school students in South Florida. During the five-week "Summer Camp", students will be involved with research topics through presentations, interactive demonstrations, and hands-on-laboratory experiences. The PI will also participate in outreach to the local community through lectures with the aim of enhancing public understanding of nanoscience and nanotechnology.