Two-dimensional Electrons in Modulation-Doped AlAs Quantum Wells

这个实验凝聚态物理项目专注于高质量、量子限制半导体结构中的电子相互作用物理。该计划包括通过分子束外延技术制造的研究，以及电子相关现象占主导地位的低温和高磁场下的电子输运特性。重点是高质量的二维（2D）电子系统局限于选择性掺杂的AlAs量子阱。砷化镓中的二维电子具有与砷化镓中的标准二维电子非常不同的参数：它们具有更大的各向异性有效质量，更大的有效g因子，并且它们占据多个导带谷。由于这些参数影响电子-电子相互作用，因此，AlAs二维电子为新的多体物理提供了一个至关重要的试验台。建议的项目主要由学生完成，包括研究生和本科生，是他们教育和培训的重要组成部分。因此，尖端技术和物理方面的优质教育被纳入研究。本研究涉及对特殊设计的半导体结构中电子相互作用的实验研究。在这些结构中，电子被限制在材料的特定层中，并且在空间上与掺杂原子（杂质）分离。因此，电子系统是非常纯净的，物理上主要是电子-电子相互作用，而不是电子-杂质相互作用。这样的系统充当了一些涉及相互作用的最令人兴奋的物理学的试验场。在这项工作中探索的特殊系统涉及到砷化铝层中电子的限制。在砷化镓（GaAs）层中，电子的参数与传统的电子系统有很大的不同，因此新的现象有望发生。这个研究项目包括通过分子束外延技术的制造，以及电子相互作用现象占主导地位的低温和高磁场下的电子输运特性的研究。研究的主要部分将由研究生和本科生进行。学生们将在密切的监督下，对固态物理学中一些最令人兴奋和最具挑战性的问题进行最先进的研究。先进的层状半导体结构的制造和物理都处于当今科学技术的前沿。因此，虽然拟议研究的主题是基础的，但在这一领域受过良好训练和教育的学生将是美国乃至世界其他地区的宝贵资源。

This experimental condensed matter physics project focuses on electron interaction physics in high-quality, quantum-confined semiconductor structures. The program includes studies of both fabrication, via molecular beam epitaxy technique, and of electronic transport properties at low temperatures and high magnetic fields where electron correlation phenomena dominate. The emphasis is on high-quality two-dimensional (2D) electron systems confined to selectively-doped AlAs quantum wells. The 2D electrons in AlAs have parameters that are very different from those of the standard 2D electrons in GaAs: they have a much larger and anisotropic effective mass, a much larger effective g-factor, and they occupy multiple conduction band valleys. Since these parameters influence the electron-electron interaction, AlAs 2D electrons thus provide a crucial and important test-bed for new many-body physics. The proposed projects are performed primarily by students, both graduate and undergraduate, and form a crucial part of their education and training. Quality education, in cutting edge technology and physics, is therefore integrated into the research.This research involves an experimental study of interaction between electrons in specially designed semiconductor structures. In these structures, the electrons are confined to specific layers in the material and are spatially separated from the dopant atoms (impurities). As a result, the electron system iis very pure and the physics is dominated by electron-electron interaction rather than electron-dirt (-iimpurity) interaction. Such systems serve as a testing ground for some of the most exciting physics involving interaction. The particular system that is explored in this work involves the confinement of electrons in an AlAs (aluminum arsenide) layer. The electrons in AlAs have parameters that are very different from the more conventional system of electrons in a GaAs (galium arsenide) layer so that new phenomena is expected to occur. This research program includes studies of both fabrication, via molecular beam epitaxy technique, and of electronic transport properties at low temperatures and high magnetic fields where electron interaction phenomena dominate. The major part of the research will be performed by graduate and undergraduate students. The students will do state-of-the-art research, under close supervision, on some of the most exciting and challenging problems in solid state physics. Both the fabrication and the physics of advanced layered semiconductor structures are at the forefront of today's science and technology. Therefore, while the subject of the proposed research is fundamental, well-trained and educated students in this field will be invaluable resources for the US as well as the rest of the world.