Nanoscale Optoelectronics with Polarization and Bandgap Engineered Nitride Nanowire/Silicon Heterostructures

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Technical. This project addresses growth and optoelectronic properties of optically active III-V Nitride nanowire semiconductor heterostructures on silicon substrates. Based on the fundamental studies and combination of polarization and bandgap engineering, demonstration of ultraviolet and visible light emitters and detectors integrated with silicon substrates is expected. Nanowires will be grown without foreign metal catalyst particles, and the underlying silicon substrate will be used to tunnel-inject holes into the III-V nitride nanowires that are difficult to dope p-type with traditional acceptor dopants. Through the wide range of bandgaps viable with AlInGaN alloys, multicolor detectors and emitters will be grown and characterized. A major part of the pro-ject involves structures where the nanowires do not need to be broken off (or 'harvested'), but to exploit the intrinsic structure to develop applications that are not easily achievable either with III-V nitride thin films, or with silicon alone. These hybrid heterostructures provide advantages of dissimilar materials without the constraint of lattice-matching. Non-Technical. The project addresses fundamental research issues in a topical area of electronic/photonic materials science having technological relevance. The project will involve undergraduate students during the academic semesters as well as the summer. Theoretically oriented students will be involved in the project at the level of simulations of band diagrams and device structures. Experimentally inclined students will be involved at the level of fabrication of nanowire/silicon devices and their characterization. They will work directly with graduate students and the PIs by attending meetings and presenting their work. Depending on the results, the undergraduate students will be encouraged to publish their work. The project will result in the training of graduate students in a forefront area of nanoelectronics. Additional to expanding the existing outreach programs that the PIs are managing, two new activities are proposed with a special focus on under-represented groups: 1) experimental demonstration of nanoscale scanning probe techniques at the Expanding Your Horizon workshops where young school girls gather for their early exposure to how science and technology are employed in various careers, and 2) re-search projects designed for women undergraduate students under the Dual Degree Program at St. Mary's College. The dissemination of research results by publications and presentations at conferences, and its inclusion in courses taught by the investigators will ensure the outreach of the research proposed to the widest possible audience.