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.