Nanopillar quantum cascade lasers

纳米柱量子级联激光器

• 批准号: 1509801
• 负责人: Benjamin Williams
• 金额: $ 45万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1509801&HistoricalAwards=false
• 关键词: Nanopillar; quantum; cascade; lasers

Abstract Title: Nanopillar quantum cascade lasersNon-technical descriptionThis research addresses the challenge of making terahertz semiconductor laser sources that operate at room temperature in the 1-5 THz range. Compact chip-scale sources of terahertz radiation that operate with both reasonably high output power (milliwatts or more) are desired for a range of spectroscopy and imaging applications. Examples include molecular gas sensing in the field of astrophysics and atmospheric science (for example investigation of star formation), imaging in the biological and medical sciences (for example burn and skin tumor imaging), security screening and illicit material detection (for example explosive and drug identification), and non-destructive evaluation (for example corrosion monitoring, delamination and void detection in films and coatings). Existing THz quantum-cascade lasers only operate at cryogenic temperatures which requires extra cooling, larger size, and increased power consumption. The intellectual merit of this proposal lies in the development of a new material system for such lasers "nanopillar quantum dots" that has the potential to increase operating temperatures to room temperature by suppressing unwanted interactions of the electrons with lattice vibrations. The broader impacts are addressed at several levels including undergraduate and graduate research experiences, dissemination of results, technology advancement. Outreach to underrepresented minorities will specifically occur through the development of research projects for a course designed for the recruitment and retention of underrepresented minority engineering undergraduates. Technical DescriptionThe intellectual merit of this proposal resides in two innovative components: the use of nanopillar quantum-dots for intersubband cascade lasers, and catalyst-free selective area semiconductor nanopillar epitaxy of quantum dot heterostructures. Use of quantum dots to create discrete energy levels can dramatically suppress nonradiative scattering of electrons by optical-phonon. Hence, a terahertz laser based discrete states in quantum-dots is expected to solve a fundamental limitation of conventional planar THz quantum-cascade lasers, where non-radiative phonon-assisted relaxation prevents room temperature operation. In this proposed concept, carriers would flow longitudinally down the length of a nanowire ensemble in a cascaded dot-to-dot tunneling regime without coupling with two-dimensional states. Selective-area MOCVD epitaxy without metal catalysts will be used to grow high-aspect ratio InAs/InAsP semiconductor nanopillar arrays using lithographically defined oxide growth masks. Lateral quantum confinement is determined by the mask feature dimension and the presence of an InP passivating shell heterostructure; longitudinal confinement is determined by the axial heterostructure. A collaborative research effort is proposed in three overlapping stages: (i) growth of axial and core/shell heterostructures in InAs/InAsP nanopillars for the formation of coupled-quantum wells and dots, (ii) investigation of the intersubband optical and transport properties, and (iii) investigation of nanopillar cascade designs for electroluminescence, stimulated emission, and quantum cascade laser demonstration.

摘要标题：纳米量子级联激光器非技术描述这项研究解决了制造在室温下工作在1-5 THz范围内的太赫兹半导体激光器的挑战。紧凑型芯片规模的太赫兹辐射源在一系列光谱和成像应用中都需要具有相当高的输出功率(毫瓦或更高)。例如，天体物理学和大气科学领域的分子气体传感(例如恒星形成的调查)、生物和医学领域的成像(例如烧伤和皮肤肿瘤成像)、安全筛查和非法材料检测(例如爆炸物和毒品识别)以及非破坏性评估(例如薄膜和涂层中的腐蚀监测、分层和空洞检测)。现有的太赫兹量子级联激光器只能在低温下工作，这需要额外的冷却、更大的尺寸和更高的功率消耗。这一提议的智力价值在于为这类激光器开发了一种新的材料系统--纳米量子点，它有可能通过抑制电子与晶格振动的不必要相互作用，将工作温度提高到室温。更广泛的影响在几个层面上得到解决，包括本科生和研究生的研究经验、成果的传播、技术进步。具体而言，将通过为招聘和留住任职人数不足的少数民族工程本科生而设计的课程的研究项目，向任职人数不足的少数群体开展外联活动。这一提议的智力优势在于两个创新部分：将纳米量子点用于子带间级联激光器，以及无催化剂的选择区域半导体纳米管外延量子点异质结构。使用量子点来创建离散能级可以极大地抑制光学声子对电子的非辐射散射。因此，基于太赫兹激光器的量子点离散态有望解决传统平面太赫兹量子级联激光器的一个基本限制，即非辐射声子辅助弛豫阻止室温工作。在这个提出的概念中，载流子将以级联的点对点隧道机制沿纳米线系综的长度纵向流动，而不与二维态耦合。没有金属催化剂的选择性区域MOCVD外延将被用来使用光刻定义的氧化物生长掩模来生长高深宽比的InAs/InAsP半导体纳米管阵列。横向量子限制由掩模特征尺寸和InP钝化壳层异质结构的存在决定，纵向限制由轴向异质结构决定。合作研究分三个阶段进行：(I)在InAs/InAsP纳米管内生长轴向和核/壳异质结构以形成耦合量子阱和量子点；(Ii)研究亚带间的光学和输运性质；(Iii)研究用于电致发光、受激发射和量子级联激光演示的纳米管级联设计。