Metal Sulfide Semiconductor Nanowires and "Wired" Nanoparticles

该项目涉及两种类型的基于金属硫化物(硫化镉、硫化铅、硫化铜和硫化银)的纳米结构系统：1)超长(500微米)金属硫化物纳米线阵列和2)由金属纳米线连接段连接的线状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在过去两年开发的一项技术。这些结构的合成和表征(包括结构和化学结构)将作为项目的第一阶段进行。在第二阶段中，将通过将纳米线从高度有序的热解石墨(HOPG)表面转移到玻璃衬底上，并将金属接触蒸发到转移的线阵列的末端来研究这些材料的导电、光导和电致发光。最近的工作证明了这种方法的可行性。我们试图从根本上理解金属硫化物半导体的体电子结构是如何表现在多晶一维线的光学和电学性质上的。本研究中将合成的超长导线将使直接电测量导线阵列中的导电性成为可能，并可能在这些系统中电激发发光。对多晶一维半导体纳米线性质的更广泛的理解和基本的见解是这些研究的预期结果。该项目解决具有高度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对教育的高度重视，强调大学和高中生参与的研究和教育的一体化。国际和平协会在UCI校园附近的大学高中建立了学生外展活动。这项提议的一个教育目标是扩大这一外展计划，以包括每年额外1-2名高中学生，这些学生来自Newport Mesa和Santa Ana联合学区内经济困难学生高度集中的高中。它计划通过与NSF资助的联合科学家、学生和学校的教师外联合作组织或Focus合作来确定潜在的研究候选人！加州大学洛杉矶分校的项目。每个学生都在暑期跟随一名研究生做学徒，直到他们培养开展独立研究项目所需的研究技能。这个项目将在暑假期间进行，并可能在周末和放学后延伸到学年。研究项目将根据学生的能力和兴趣而量身定做。一个样本项目可能包括合成一种类型的半导体纳米线，并使用扫描电子显微镜和EDX(能量色散X射线分析)元素分析对这些纳米线进行表征。

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.***