Polarization-Insensitive Double Quantum Wells for Electro-Optical Applications

该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。具体来说，我们将研究夹在InxA11-xAs势垒之间的拉伸应变GaAs量子阱的生长和电子-空穴相互作用。通过这种配置，我们能够控制光响应的偏振特性，同时保持与gaas基加工的兼容性。我们最近在单量子阱中的工作已经证明了这种结构在光学响应极化很重要的器件中使用的潜力。在这个为期12个月的项目中，我们将确定最佳的MBE生长条件，以增强室温下的光学响应，这是器件适用性所必需的。利用带偏置建模与光学技术相结合来检查不同屏障/井宽和应变的结构，我们将探索最适合进一步技术发展的DQW设计。主要的生长和表征方法将分别是分子束外延（MBE）和光致发光（PL）光谱。这些将得到电气分析技术的支持，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。最佳生长条件将通过MBE控制（如衬底温度、生长速率、V/III比、As超压）和基于结构（如井/势垒宽度、应变、掺杂）参数的变化来检验。在我们最初的工作中，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，后者提供与InA1As势垒层的晶格匹配。利用温度、激发强度和激发波长以及偏振态变化的PL测量，将用于阐明由于量子阱的电子-空穴跃迁选择规则而通常无法观察到的现象。我们在MBE和PL方面的平行目标将为基于这些DQW和类似结构的实用设备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的合作研究项目。＊＊＊

9633780 Daniels-Race 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 excitat ion wavelength, 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. ***