Polarization-Insensitive Double Quantum Wells for Electro-Optical Applications

9633769麦克尼尔这个项目的目标是开发偏振不敏感的双量子阱(DQW)结构，用于光信号的调制、检测和放大。具体地说，我们将研究夹在InxA11-xAs势垒之间的拉伸应变量子阱的生长和电子-空穴相互作用。通过这种配置，我们能够控制光学响应的偏振特性，同时保持与基于GaAs的工艺的兼容性。这种结构在光学响应的偏振很重要的器件中的应用潜力已经被我们最近在单量子阱中的工作所证明。在这个12个月的项目中，我们将确定最佳的MBE生长条件，以增强器件在室温下的光学响应，这是器件适用性所必需的。使用带偏移建模和光学技术来检查不同势垒/势垒宽度和应变的结构，我们将探索最适合进一步技术开发的DQW设计。生长和表征的主要方法将分别是分子束外延(MBE)和光致发光(PL)光谱。这些将得到电子分析技术的支持，例如霍尔和电流-电压测量、X射线衍射以及透射和扫描电子显微镜。最佳的生长条件将通过MBE控制的参数(例如衬底温度、生长速度、V/III比、超压)和基于结构的参数(例如势垒/势垒宽度、应变、掺杂)的变化来检验。就像我们最初的工作一样，我们的大部分研究将是作为砷化镓衬底生长的结构。然而，我们也会将这些结构的光学特性与那些生长在三元衬底上的结构进行比较，这些结构提供了与InAlAs势垒层的晶格匹配。使用温度、激发强度和激发波长以及偏振态变化的PL测量将被用来解释由于量子阱的电子-空穴跃迁选择规则而通常不能观察到的现象。我们在MBE和PL方面的并行目标将为基于这些DQW和类似结构的实用器件的开发奠定必要的基础。这是杜克大学的Theda Daniels-Race和北卡罗来纳大学教堂山分校的Laurie McNeil合作的研究项目。***

9633769 McNeil The goal of this project is to develop polarization-insensitive double quantum well (DQW) structures for applications in the modulation, detection, and amplification of optical signals. Specifically, we will investigate the growth and electron-hole interactions of tensile strained GaAs quantum wells sandwiched between InxA11-xAs barriers. With this configuration we are able to control the polarization characteristics of the optical response while maintaining compatibility with GaAs-based processing. The potential for the use of such structures in devices wherein polarization of the optical response is important has been demonstrated by our recent work in single quantum wells. In this 12 month project we will determine optimum MBE growth conditions which enhance the optical response at room temperature, as is required for device applicability. Using band-offset modeling in conjunction with optical techniques to examine structures of different barrier/well widths and strains, we will explore the DQW designs most suitable for further technological development. The primary methods of growth and characterization to be employed will be molecular beam epitaxy (MBE) and photoluminescence (PL) spectroscopy, respectively. These will be supported by electrical analysis techniques such as Hall and current-voltage measurements, X-ray diffraction, and both transmission and scanning electron microscopy. Optimal growth conditions will be examined by variation of MBE controlled (e.g.-substrate temperature, growth rate, V/III ratio, As overpressure) and structurally based (e.g.-well/barrier widths, strain, doping) parameters. As in our initial work, most of our studies will be of structures grown as GaAs substrates. However, we will also compare the optical characteristics of these structures to those of structures grown on ternary substrates, which provide lattice matching with the InA1As barrier layers. PL measurements, using temperature, excitation intensity and excitation wa velength, and polarization state variations, will be used to elucidate phenomena normally unobservable due to electron-hole transition selection rules for quantum wells. Our parallel goals with respect to the MBE and PL efforts will lay the necessary groundwork for development of practical devices based on these DQW's and similar structures. This is a collaborate research project between Theda Daniels-Race of Duke University and Laurie McNeil of the University of North Carolina-Chapel Hill. ***