CAREER: Nanoscale Composition Control and Characterization of One-Dimensional Semiconductor Nanostructures

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The primary objectives of this CAREER project are: (1) control of electronic and magnetic properties of compositionally modulated semiconductor nanowires via electronic and magnetic doping; (2) ability to map the composition of doped nanowires and nanowire heterostructures with single atom sensitivity and sub-nanometer resolution using atom-probe microscopy; (3) to explore unique local electronic and magnetic characteristics of dopants in one-dimensional semiconductor nanowire hosts using catholuminescence microscopy and scanning probe techniques; and (4) to combine scanning probe microscopy with electrical transport measurements to relate local properties and distribution of individual electronic and magnetic dopant atoms to novel electrical, optical, and magnetic properties of individual semiconductor nanowires. The approach is to first establish the physical limits of controlled doping in semiconductor nanowires through inorganic synthesis; to then demonstrate how novel global electronic and magnetic properties of a single nanowire arise from local properties of dopant atoms and heterointerfaces in a one-dimensional host material, examining, for example, how altered screening lengths in 1-d systems affect electronic properties of nanowire homojunctions and heterojunctions. Additionally, spin ordering of magnetic dopant atoms mediated by itinerant carriers with a 1-d density of states will be explored. Nanomaterials understanding, characterization, and control achieved are expected to advance the science and technology of nanomaterials.%%% The project addresses fundamental research issues in electronic/photonic materials science having technological relevance. The project is interdisciplinary involving chemistry, physics, engineering and materials science, and has strong potential technological relevance. The project is also expected to enhance the infrastructure for research and education. Outreach efforts, including research experiences for under-represented groups and women from female colleges, are an integral part of the planned activities. Within the undergraduate curriculum, a course is being developed that will integrate laboratory research experience into a course on nanoscale surface characterization to train members of the future workforce in an area of strategic importance. Additionally, the PI works with a diverse group of high school teachers that reach a diverse student population in the Chicago Public School system. It is his goal to create more opportunities for all students in the greater Chicago area and beyond to benefit from the broad resources at Northwestern University.***