Metal Sulfide Semiconductor Nanowires and "Wired" Nanoparticles

该项目涉及两种类型的基于金属硫化物（CdS，PbS，Cu 2S和Ag 2S）的纳米结构系统：1）超长（500 μ m）金属硫化物纳米线阵列和2）通过金属纳米线连接段连接的有线金属硫化物纳米颗粒。这些系统的合成方法依赖于电化学阶梯边缘装饰，这是PI在过去两年中开发的一种技术。这些结构的合成和表征（结构和化学）将作为项目的第1阶段进行。在第2阶段，这些材料的导电性、光电导性和电致发光将通过将纳米线从HOPG（高度有序热解石墨）表面转移到玻璃基板上并将金属接触蒸发到转移的线阵列的末端上来研究。最近的工作证明了这种方法的可行性。寻求基本的理解是如何体现在多晶一维线的光学和电学性能的金属硫化物半导体的体电子结构。在这项研究中合成的超长导线将使直接测量导线阵列中的导电性成为可能，并有可能在这些系统中电激发发光。更广泛的理解和多晶一维半导体纳米线的性质的基本见解是从这些研究的预期成果。该项目解决了具有高技术相关性的电子材料专题领域的基础研究问题。该项目的一个重要特点是高度重视教育，强调大学和高中学生参与的研究和教育的一体化。PI已经在UCI校园附近的大学高中开展了外联活动。该提案的一个教育目标是扩大这一推广方案，每年从纽波特梅萨和圣安娜联合学区内经济困难学生高度集中的高中再招收1-2名高中生。它计划通过与NSF资助的教师外联合作联合科学家，学生和学校，或焦点接口确定研究的潜在候选人！在UCI的节目。每个学生在夏季与一名高年级研究生一起担任学徒，直到他们培养出独立研究项目所需的研究技能。该项目将在夏季的剩余时间进行，并可能在周末和放学后延长到学年。研究项目将根据学生的能力和兴趣量身定制。一个样本项目可能涉及一种半导体纳米线的合成，以及使用扫描电子显微镜和EDX（能量色散X射线分析）元素分析对这些线的表征。

This project addresses two types of nanostructured systems based on metal sulfides (CdS, PbS, Cu2S, and Ag2S): 1)Arrays of ultra-long ( 500 um) metal sulfide nanowires and 2)Wired metal sulfide nanoparticles linked by metal nanowire connecting segments. The approach to the synthesis of these systems relies on Electrochemical Step Edge Decoration, a technique developed by the PI over the past two years. The synthesis and characterization (both structural and chemical) of these structures will be carried out as Phase 1 of the project. In Phase 2 electrical conduction, photoconductivity, and electroluminescence of these materials will be investigated by transferring the nanowires from HOPG (Highly Ordered Pyrolytic Graphite) surfaces onto glass substrates and evaporating metal contacts onto the ends of the transferred wire arrays. Recent work has demonstrated feasibility of the approach. Fundamental understanding is sought of how the bulk electronic structure of metal sulfide semiconductors is manifested in the optical and electrical properties of polycrystalline 1-D wires. The ultra-long wires to be synthesized in this study will make possible direct electrical measurements of conduction in wire arrays with the possibility of electrical excitation of luminescence in these systems. Broader understanding and fundamental insights into the properties of polycrystalline 1-D semiconductor nanowires are anticipated outcomes from these studies. %%% The project addresses basic research issues in a topical area of electronic materials with high technological relevance. An important feature of the project is the strong emphasis on education, with emphasis on integration of research and education involving university and high school students. The PI has established outreach activities to students at University High School near the UCI campus. An educational objective of this proposal is to broaden this outreach program to include an additional 1-2 high-school students a year from high schools with a high concentration of economically disadvantaged students within the Newport Mesa and Santa Ana Unified School Districts. It is planned to identify prospective candidates for research by interfacing with the NSF-funded Faculty Outreach Collaborations Uniting Scientists, Students and Schools, or FOCUS! Program at UCI. Each student works as an apprentice with a senior graduate student during the summer until they cultivate the research skills necessary to embark on an independent research project. This project will take place during the balance of the summer, and possibly extend into the school year on weekends and after school. Research projects will be tailored to the abilities and interests of the students. A sample project may involve the synthesis of one type of semiconductor nanowire, and the characterization of these wires using scanning electron microscopy and EDX (Energy Dispersive X-ray Analysis) elemental analysis.***