InSb-Based Electron and Hole Systems for Charge and Spin Transport Experiments

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Technical: This project is to study the growth of semiconductor quantum wells made of indium antimonide (InSb) and to study charge and spin transport phenomena that are enabled by these materials. It attempts to address the needs of future computer technologies by focusing on InSb materials, which possess high carrier mobilities, small effective masses, and large spin-orbit effects. Such attributes imply higher operating speeds for field-effect transistors, higher operating temperatures for ballistic transport devices, and the opportunity for spintronic devices that could provide new routes for computation and data storage. Both n-type and p-type quantum wells with high carrier mobilities are required for transistors in logic applications. The electrical properties of the proposed metamorphic heterostructures, on GaAs and Si substrates, will be optimized in this project through defect filtering by interlayers and judicious design of strain-balanced barrier and well layers. Maximum strain is particularly important for p-type quantum wells, where a small effective mass, and consequently a high mobility, relies on the degree to which degeneracy is lifted in the valence bands. Magneto-optics experiments are designed to characterize the effects of strain and confinement on the effective mass of holes in InSb. The optimization of the growth of quantum wells will make possible studies of strong spin-orbit coupling effects via weak anti-localization experiments, carrier focusing devices, and spin interferometers.Non-technical: The project addresses basic research issues in a topical area of materials science with high technological relevance, and is expected to provide new scientific understanding of spin-orbit coupling of not only InSb, but zinc blende semiconductors in general. The research group at the University of Oklahoma is one of the only two groups worldwide who are able to grow high-quality InSb heterostructures needed by many scientists in studying fundamental physics and materials science. This project will also contribute to the preparation of students, including members of underrepresented groups, for employment in areas of technological importance.