Shape-Dependent Electronic and Optical Properties in Semiconductor Nanowires

技术：该项目涉及PbSe纳米线的合成、加工和表征。PbSe纳米线与控制的大小和形状（直，锯齿形，螺旋形，和分支拓扑结构）将通过湿化学方法合成和电子和光学研究探针的大小和形状依赖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、探测线均匀性，并测量预期的一维偏振。将纳米线暴露于选定的电荷转移掺杂剂将使得能够对线进行n掺杂和p掺杂，并且允许探测电子和空穴的传输。结合使用温度依赖性、空间和时间分辨的光电导性和纳米级电学测量，将研究电子结构沿着纳米线长度的均匀性以及相关的纳米级粗糙度对长度尺度（~10 nm）的影响，所述长度尺度小于激子（~46 nm）、电子（~23 nm）和空穴（~23 nm）的PbSe玻尔半径。这些测量将用于表征不同的拓扑结构，激子和电荷捕获和散射，影响弹道传输的长度尺度，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：该项目涉及电子/光子材料科学领域的基础研究问题，具有高度的技术相关性。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和特性的教学，并为本科生和研究生提供重要的跨学科研究机会。PI强调跨越化学和物理概念的教学课程，这些概念对于材料，化学，物理和电气社区之间的桥梁非常重要，这些社区存在令人兴奋的研究机会。她正在开发一门关于半导体物理以及材料和器件的电子，光学，磁性和生物学特性的新课程。此外，她积极参与与学生在论坛上发言，鼓励他们思考自己的职业生涯。她还在美国大学的部门和跨学科的女化学家团体中促进非正式的午餐和咖啡会议。宾夕法尼亚大学和其他学术机构。

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.