Optical and Far Infrared Studies of Semiconductor Heterostructures

半导体异质结构的光学和远红外研究

• 批准号: 0072897
• 负责人: Margaret Dobrowolska
• 金额: $ 31.5万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-15 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0072897&HistoricalAwards=false
• 关键词: Optical; Far; Infrared; Studies; Semiconductor

The project consists of three parts, all of them involving semiconductor heterostructures whose properties are determined almost entirely by electron spin. (1) Fabricate, and carry out optical studies of self-assembled magnetic semiconductor quantum dots (QDs) achieved by introducing Mn into the CdSe/ZnSe QD system. This effort will focus on the understanding and control of the self-assembly process, with emphasis on the morphology, uniformity of composition, and control of Mn incorporation. Optical studies will concentrate on the exchange interaction in zero-dimensional systems, on the effect of a reduced number of magnetic nearest-neighbors in the QD geometry, and on determining the (expectedly very long) spin lifetimes in such systems. (2) Fabricate and perform optical studies of ferromagnetic semiconductors and their multilayers. The discovery of ferromagnetism in III-Mn-V alloys is a major breakthrough that holds out possibilities of integrating giant spin-related effects into III-V-based electronics and optoelectronics. The problem of the large density of defects that form when Mn is introduced into the III-V lattice will be addressed by a series of strategies for MBE growth of III-V based ferromagnetics. Optical tests of these systems will focus specifically on improving the optical quality of these materials via defect reduction and optimization of p-type doping. (3) Bragg-confining systems based on diluted magnetic semiconductor (DMS) multilayers will be investigated. These systems offer the possibility of tuning (via an applied magnetic field) the relative band alignment between the constituent layer materials. This tunability can be used for controlling the de Broglie wavelength of electrons and/or holes within the structure, and thus for tuning their Bragg localization. Since in DMS-based systems the tunability of Bragg localization is spin-specific, the structures developed in the program will serve as prototypes for spin-filtering devices that may find important application in spin-based electronics. This research will provide training for graduate students in areas of nanoscience and spin-based electronics, thus meeting U.S. manpower needs in two important and rapidly developing areas of technology.%%% Traditional semiconductor electronics is based entirely on the electron charge and its response to applied electric signals. The electron, however, is also characterized by another property: the spin. Recent experiments have demonstrated that this latter property holds out certain advantages which make spin-based nanostructures attractive as candidates for the next generation of electronic devices. Although one can already envision future applications of spin-based electronics ("spintronics") in detector systems, ultra-fast switches and quantum computing, many fundamental issues need to be resolved before such devices can become reality. This research deals with three inter-related areas involving semiconductor heterostructures whose properties are determined almost entirely by electron spin: Controlled fabrication of spintronics materials, optical characterization of these materials, and development of techniques for the effective identification of different spin states from one another. Successful completion of these tasks will be major contributions to the scientific understanding of spintronics processes and their incorporation in practical technological devices. This research will be performed with graduate students and postdoctoral research associates. They will receive training in areas of nanoscience and spin-based electronics in preparation for their entry into the scientific and technological workforce. ***

该项目由三个部分组成，所有部分都涉及半导体异质结构，其性质几乎完全由电子自旋决定。 （1）通过将MN引入CDSE/ZNSE QD系统实现的自组装磁性半导体量子点（QD）进行制造并进行光学研究。这项努力将集中于对自组装过程的理解和控制，重点是形态，组成的统一以及对MN掺入的控制。 光学研究将集中在零维系统中的交换相互作用上，QD几何形状中磁性近脑的数量减少，并确定此类系统中（预期非常长的）自旋寿命。 （2）对铁磁半导体及其多层制造和进行光学研究。在III-MN-V合金中发现铁磁性是一个重大突破，它使与基于IIII-V的电子和光电子学的巨型旋转效应相结合。将MN引入III-V晶格时形成的较大缺陷密度的问题将通过一系列基于III-V的铁磁性生长的策略来解决。这些系统的光学测试将专门针对通过降低和优化P型掺杂来提高这些材料的光学质量。 （3）将研究基于稀释的磁性半导体（DMS）多层的布拉格融化系统。这些系统提供了（通过施加的磁场）调整组成层材料之间的相对带比对的可能性。可调节性可用于控制结构内电子和/或孔的de broglie波长，从而调整其布拉格定位。 由于在基于DMS的系统中，Bragg定位的可调节性是自旋特异性的，因此该程序中开发的结构将用作旋转过滤设备的原型，这些设备可能在基于自旋的电子设备中找到重要的应用。这项研究将为纳米科学和基于旋转的电子产品领域的研究生提供培训，从而满足美国技术人员的人力需求。%% %%传统的半导体电子电子完全基于电子费用及其对应用电信号的响应。 然而，电子也具有另一个特性：自旋。 最近的实验表明，后一种属性具有某些优势，这些优势使基于自旋的纳米结构作为下一代电子设备的候选者有吸引力。 尽管已经可以设想基于旋转的电子设备（“ Spintronics”）在检测器系统，超快速开关和量子计算中的未来应用，但是在此类设备成为现实之前，需要解决许多基本问题。这项研究涉及涉及半导体异质结构的三个相互关联区域，这些区域几乎完全由电子自旋确定：旋转型材料的受控制造，这些材料的光学表征以及开发技术以有效地识别不同旋转状态的技术。这些任务的成功完成将是对旋转过程及其在实用技术设备中的科学理解的主要贡献。这项研究将与研究生和博士后研究伙伴一起进行。他们将接受纳米科学和基于旋转电子产品的领域的培训，以准备进入科学和技术劳动力。 ***