Multicomponent Correlated Electron Systems: Fabrication andPhysics

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w:\awards\awards96\*.doc 9623511 Shayegan This research involves a study of the materials science and physics of the growth of very high-quality gallium- arsenide/aluminum-gallium-arsenide hetero-junction structures using the molecular beam epitaxy technique, and the new electron interaction physics expected to emerge in such ideal systems. The project emphasized studies of novel quasi-two-dimensional electron and hole systems with an additional degree of freedom. These include systems which contain two or more layers of electrons in close proximity so that interlayer Coulomb interactions are strong, and electron systems in aluminum- arsenide quantum wells where the conduction band has a multi- valley degeneracy. The additional degree of freedom in these structures is expected to lead to new collective states which we plan to probe via low temperature magnetotransport measurements. %%% An experimental investigation of electron interaction physics in quantum-confined semi-conductor hetero-structures will be made. The emphasis of the program is on both the fabrication, via the molecular beam epitaxy technique, and the electronic transport measurements at low temperatures and high magnetic fields where electron correlation effects dominate. The proposed systems, name, novel high-quality electron and hole systems in selectively- doped gallium-arsenide/aluminum-gallium-arsenide hetero-junction structures, are among the cleanest (lowest-disorder) carrier systems available. Such structures provide a crucial and important test-bed for new many-body physics. The results can also have an impact on the realization of new devices whose fabrication and/or operation is based on semiconductor structures of similar type. ***