Shape-Dependent Electronic and Optical Properties in Semiconductor Nanowires

技术：该项目致力于PbSe纳米线的合成、加工和表征。我们将用湿化学方法合成尺寸和形状可控的PbSe纳米线(直线型、Z字型、螺旋型和分枝型)，并对其进行电子学和光学研究，以探测与尺寸和形状有关的电荷输运和激子相互作用。将收集吸收和发射线宽度和能量，以测试有效质量模型、探针线的均匀性和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能够进行n掺杂和p掺杂，并允许探测电子和空穴的传输。结合温度依赖、空间和时间分辨的光电导测量和纳米尺度的电学测量，我们将研究沿纳米线长度方向的电子结构的均匀性，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)的影响。这些测量将被用来表征不同的拓扑结构、激子和电荷捕获和散射，它们影响弹道传输的长度尺度、电子和空穴载流子的迁移率以及激子的吸收、发射和扩散系数。非技术性：该项目涉及具有高度技术相关性的电子/光子材料科学专题领域的基础研究问题。研究活动将有助于扩大纳米材料的知识库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的重点是教授跨越化学和物理概念的课程，这些概念对于在材料、化学、物理和电气社区之间架起桥梁非常重要，在这些社区中，存在着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设备的电子、光学、磁性和生物特性的新课程。此外，她还积极参与论坛中与学生的交谈，鼓励他们思考自己的职业。她还促进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团体之间的非正式午餐和咖啡会议。

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.