Multicomponent Correlated Electron Systems: Fabrication andPhysics

本研究涉及到利用分子束外延技术生长高质量砷化镓/砷化铝镓异质结结构的材料科学和物理学研究，以及在这种理想体系中有望出现的新的电子相互作用物理学。该项目重点研究具有额外自由度的新型准二维电子和空穴系统。这些系统包括包含两层或更多层电子的系统，它们非常接近，因此层间的库仑相互作用很强，以及砷化铝量子阱中的电子系统，其导带具有多谷简并。这些结构的额外自由度有望导致新的集体状态，我们计划通过低温磁输运测量来探测。本文将对量子约束半导体异质结构中的电子相互作用物理进行实验研究。该计划的重点是通过分子束外延技术制造，以及在电子相关效应占主导地位的低温和高磁场下的电子输运测量。所提出的系统，名称，选择性掺杂砷化镓/铝砷化镓异质结结构中的新型高质量电子和空穴系统，是可用的最干净（最低无序）载流子系统之一。这种结构为新的多体物理学提供了一个至关重要的试验台。该结果还可以对基于类似类型的半导体结构的制造和/或操作的新器件的实现产生影响。＊＊＊

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. ***