Shape-Dependent Electronic and Optical Properties in Semiconductor Nanowires

技术：本项目研究PbSe纳米线的合成、加工和表征。将通过湿化学方法合成尺寸和形状可控的PbSe纳米线（直、之字形、螺旋和分支拓扑），并对其进行电子和光学研究，以探测尺寸和形状相关的电荷传输和激子相互作用。将收集吸收和发射线宽和能量，以测试有效质量模型，探测导线均匀性，并测量预期的一维极化。将纳米线暴露在选定的电荷转移掺杂剂中，将使纳米线的n和p掺杂成为可能，并允许探测电子和空穴的输运。结合温度依赖、空间和时间分辨的光电性和纳米尺度的电学测量，将研究沿纳米线长度的电子结构均匀性以及相关的纳米尺度粗糙度对激子（~46 nm）、电子（~23 nm）和空穴（~23 nm）小于PbSe玻尔半径的长度尺度（~10 nm）的影响。这些测量将用于表征不同拓扑结构，激子和电荷捕获和散射，它们影响弹道输运的长度尺度，电子和空穴载流子迁移率，以及激子的吸收、发射和扩散率。非技术性：项目涉及电子/光子材料科学领域的基础研究问题，具有较高的技术相关性。这些研究活动将有助于扩大纳米材料的知识基础和低维材料物理与性质的教学，并为本科生和研究生提供重要的跨学科研究机会。PI的教学重点是跨越化学和物理概念的课程，这对于在材料，化学，物理和电气社区之间架起桥梁很重要，因为这些社区存在令人兴奋的研究机会。她正在开设一门关于半导体物理以及材料和器件的电子、光学、磁性和生物特性的新课程。此外，她还积极参与论坛与学生交谈，鼓励他们思考自己的职业。她还在宾夕法尼亚大学和其他学术机构的部门和跨学科女性化学家小组之间推广非正式的午餐和咖啡会议。

Technical: This project addresses synthesis, processing and characterization of PbSe nanowires. PbSe nanowires with controlled size and shape (straight, zig-zag, helical, and branched topologies) will be synthesized via wet chemical methods and studied electronically and optically to probe size and shape dependent charge transport and excitonic interactions. Absorption and emission linewidths and energies will be collected to test effective mass models, probe wire homogeneity, and measure expected one-dimensional polarizations. Exposing the nanowires to selected charge transfer dopants will enable n- and p-doping of the wires and allow the transport of both electrons and holes to be probed. Using, in combination, temperature-dependent, spatially and temporally resolved photoconductivity and nanoscale electrical measurements, uniformity in electronic structure along the lengths of the nanowires and the influence of correlated, nanoscale roughness on a length scale (~10 nm) smaller than that of the PbSe Bohr radii for excitons (~46 nm), electrons (~23 nm), and holes (~23 nm) will be investigated. These measurements will be used to characterize in different topologies, exciton and charge trapping and scattering that impact the length scale for ballistic transport, the electron and hole carrier mobilities, and the absorption, emission, and diffusivity of excitons. Non-technical: The project addresses basic research issues in a topical area of electronic/photonic materials science with high technological relevance. The research activities will help to expand the knowledge base in nanomaterials and the teaching of low-dimensional materials physics and properties, and provide important interdisciplinary research opportunities for undergraduate and graduate students. The PI places emphasis on teaching courses that span chemical and physical concepts important to bridging between Materials, Chemical, Physical, and Electrical communities where exciting research opportunities exist. She is developing a new course on semiconductor physics and on the electronic, optical, magnetic, and biological properties of materials and devices. Additionally she is actively involved in speaking with students in forums that encourage them to think about their careers. She also promotes informal lunch and coffee meetings among departmental and interdisciplinary women chemist groups at U. Penn and other academic institutions.