Optical Studies of Tunneling and Coulomb Correlations in Mixed-Type Quantum Wells

* 技术摘要 * 本项目将研究在半导体量子阱结构中形成的电子-空穴双层，其中电子和空穴分别驻留在由薄势垒隔开的宽阱和窄威尔斯中。 这种结构的一个特点是载流子密度可以通过窄量子阱的光激发来控制。 两个密切相关的研究方向将继续进行。 第一个方向探讨了电子和空穴之间的多体库仑相关性如何影响载流子隧穿。 关联诱导隧穿也将作为激子非线性光学的一种新机制。 第二个方向旨在设计一个局部空穴阵列，实现一个二维电子在空穴晶格的静电势存在下相互作用的系统。 近期目标是使用这种可调半导体系统来探索并可能模拟强相关现象，如莫特绝缘体。 该项目将支持两名研究生在科学和技术重要领域的教育。 这项培训将为学生在学术界，工业界或政府的职业生涯做好准备。 * 非技术摘要 * 电子穿过半导体中的势垒的隧穿是一个有趣的量子力学过程，在许多电子器件中起着重要作用。 传统上，超导被认为是涉及单个电子的过程。 这个项目探索半导体纳米结构中的现象，其中隧穿过程可以强烈依赖于穿过隧穿势垒的电子之间的相互作用或相关性。 这种相关性引起的隧穿过程将被用于诸如光子开关器件的应用。 电子之间的关联效应在理解诸如高温超导体和磁性等各种有趣的物理现象中也起着重要作用。 该项目的第二个和密切相关的研究方向是开发一个系统，其中二维半导体结构中的电子在带正电荷的空穴的周期性阵列的存在下相互作用。 该系统可用于改变或调整电子相关性的影响，作为研究和理解凝聚态系统中电子相关性影响的平台。 该项目将主要由两名研究生进行。 研究活动将为这些学生提供科学和技术重要性领域的扎实培训，为学生在学术界，工业界或政府的职业生涯做好准备。

****Technical abstract****This project will investigate electron-hole bilayers formed in semiconductor quantum well structures, in which electrons and holes reside respectively in wide and narrow wells separated by a thin barrier. A special feature of this structure is that the carrier density can be controlled via optical excitations of the narrow quantum well. Two closely related research directions will be pursued. The first direction explores how manybody Coulomb correlations between electrons and holes across the barrier affect carrier tunneling. The correlation-induced tunneling will also be exploited as a new mechanism for excitonic nonlinear optics. The second direction aims to engineer an array of localized holes, realizing a system where two-dimensional electrons interact in the presence of the electrostatic potential of a hole lattice. A near term goal is to use this tunable semiconductor system to explore and possibly simulate strongly-correlated phenomena such as Mott insulators. This project will support the education of two graduate students in areas of both scientific and technological importance. This training will prepare the students for careers in academia, industry, or government. ****Non-technical abstract****Tunneling of electrons across a barrier in a semiconductor is an interesting quantum mechanical process and serves important roles in many electronic devices. Tunneling is traditionally viewed as a process involving single electrons. This project explores phenomena in semiconductor nanostructures where tunneling processes can depend strongly on interactions or correlations between electrons across the tunneling barrier. This correlation-induced tunneling process will be exploited for applications such as photonic switching devices. Effects of correlations between electrons also play important roles in understanding a variety of fascinating physical phenomena such as high Tc superconductors and magnetism. A second and closely related research direction of this project is to develop a system, in which electrons in a two-dimensional semiconductor structure interact in the presence of a periodic array of positively-charged holes. This system can be used to vary or tailor effects of electron correlations, serving as a platform for investigating and understanding effects of electron correlations in condensed matter systems. This project will primarily be carried out by two graduate students. The research activities will provide these students solid training in areas of both scientific and technological importance, preparing the students for careers in academia, industry, or government.