Shape-Dependent Electronic and Optical Properties in Semiconductor Nanowires

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

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.