Two-Dimensional Electron Systems in AlAs Quantum Wells: Fabrication and Physics

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****NON-TECHNICAL ABSTRACT****One of the most fascinating areas in solid-state physics concerns new states of matter that come about primarily because of the interaction between electrons. To explore such states, one needs specimens in which the imperfections, including impurities and crystal defects, are reduced to a minimum. This individual investigator award supports a project involving the fabrication of such samples, and measurements of their novel electronic properties. The emphasis is on two-dimensional electron systems in aluminum-arsenide quantum wells. These have parameters that are very different from the commonly studied gallium-arsenide samples. An understanding of the states and phenomena observed in the new samples not only will advance our knowledge of fundamental physics, but can also lead to novel device concepts. A major component of this research is the training and education of graduate and undergraduate students in critical areas of crystal growth, semiconductor sample processing, and electrical measurements. Well-trained students in this field will be invaluable resources for the US as well as the rest of the world.****TECHNICAL ABSTRACT****This individual investigator award supports a project to explore and elucidate electron interaction physics in high-quality, quantum-confined semiconductor structures. The program includes studies of fabrication, via the molecular beam epitaxy technique, and of electronic transport properties at low temperatures and high magnetic fields where electron correlation phenomena dominate. The emphasis of the work is on novel, high-quality two-dimensional electron systems (2DESs) confined to selectively-doped AlAs quantum wells; these 2DESs have parameters that are very different from those of the standard 2DESs in GaAs. Several problems, including the influence of the spin and valley degrees of freedom on the integer and fractional quantum Hall states will be investigated. Graduate and undergraduate students will be involved with these experimental research projects. The students will be trained in crucial areas of crystal growth, fabrication, and electrical measurements.