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

****非技术摘要****固态物理学中最引人入胜的领域之一涉及主要由于电子之间的相互作用而产生的物质的新状态。为了探索这种状态，我们需要将样品中的缺陷（包括杂质和晶体缺陷）减少到最小。该个人研究者奖支持一个项目，该项目涉及制造此类样品，并测量其新颖的电子特性。重点是砷化铝量子阱中的二维电子系统。这些参数与通常研究的砷化镓样品非常不同。对新样品中观察到的状态和现象的理解不仅会提高我们对基础物理学的认识，而且还会导致新的设备概念。这项研究的一个主要组成部分是在晶体生长、半导体样品处理和电测量等关键领域对研究生和本科生进行培训和教育。在这一领域训练有素的学生将是美国和世界其他地区的宝贵资源。****技术摘要****该个人研究者奖支持一个探索和阐明高质量量子半导体结构中电子相互作用物理学的项目。该计划包括通过分子束外延技术的制造研究，以及电子相关现象占主导地位的低温和高磁场下的电子传输特性。这项工作的重点是新的、高质量的二维电子系统（2DESs），局限于选择性掺杂的AlAs量子阱；这些2des的参数与GaAs中标准的2des有很大的不同。研究了自旋和谷自由度对整数和分数阶量子霍尔态的影响等问题。研究生和本科生将参与这些实验研究项目。学生将在晶体生长、制造和电测量等关键领域接受培训。

****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.