This award will support cooperative research between Dr. Richard J. Higgins and his research group at Georgia Institute of Technology and Dr. J. C. Portal, Laboratoire de Physique des Solides, Institut National des Sciences Appliquees, Toulouse, France. Drs. Higgins and Portal will study the electronic and optoelectronic properties of 3-5 compound semiconductor heterostructures. The research will emphasize coherent (quantum) electronic effects, and identify growth and processing issues that inhibit quantum electronic devices. Two test systems will be studied: (a) coupled quantum well structures grown by molecular beam epitaxy, whose negative differential resistance promises sub-picosecond switching, but whose application is hampered by poor understanding of the physical behavior and (b) nanometer-scale structures patterned by e-beam lithography which can exhibit phase-coherent ballistic transport. Both the U.S. and French investigators have an active collaboration with shared research objectives in heterostructure magnetotransport. Techniques include magnetotransport to probe electronic behavior, pulsed light to alter defect charge state, and pressure to shift energy levels. Dr. Higgins' group brings strengths in Fourier Transform Landau Level spectroscopy. The French group has expertise in magnetotransport in heterostructures and also in high pressure measurements, valuable for heterostructure studies. The results of this research will: 1) increase understanding of semiconductor quantum-well heterostructure and quantum-size effect devices; and 2) contribute to the technology base of solid state electronics.
