OP: Terahertz Lasers Using Intersubband Transitions in non-polar III-nitrides

OP：在非极性 III 族氮化物中使用子带间跃迁的太赫兹激光器

• 批准号: 1607173
• 负责人: Michael Manfra
• 金额: $ 32万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607173&HistoricalAwards=false
• 关键词: OP; Terahertz; Lasers; Using; Intersubband

Title: Novel compact terahertz lasers utilizing polarization-free nitride semiconductors for sensing and imaging AbstractNon-technical description: This project investigates a new class of compact, efficient laser light sources operating in the long-wavelength spectral range between the infrared and the microwave ranges, known as the terahertz (THz) gap. Due to fundamental limitations of commonly used semiconductors, this range is currently inaccessible with any other semiconductor lasers. This project exploits the unique properties of nitride semiconductors. However, the nitrides also present some unique challenges related to their atomic structure and built-in electric fields. To overcome these challenges the researchers employ sophisticated modeling tools to design new laser structures. The materials are then grown using molecular beam epitaxy, a technique that allows control of the nitride thicknesses at the nanoscale, and characterized with structural and optical techniques. Finally, laser devices are fabricated and tested to study their performance under different operating conditions and to further refine the design parameters.These novel lasers have the potential to impact a number of technological applications with broad benefits to society. The applications loosely fit into one of two main categories: THz spectroscopy, and THz imaging. THz spectroscopy is currently used in fields ranging from astronomy, and atmospheric science, to plasma fusion diagnostics and bio-chemical weapons detection. THz imaging has broad applications from airport security to medical imaging. This research program also provides unique interdisciplinary research opportunities to a diverse group of students at Purdue University. Special attention is given to providing hands-on research experience to under-represented students, especially women. Outreach activities will increase the awareness and exposure of Grade 7-12 students and teachers from economically disadvantaged backgrounds in Central Indiana to the scientific content and methods of photonics.Technical description: This project develops and studies a new class of far-infrared semiconductor emitters for the 1-10 THz range, specifically operating in the reststrahlen band of GaAs (30-40 micron wavelength). These lasers utilize intersubband transitions in the conduction band of non-polar III-nitride heterostructures and employ the general operating principles of quantum cascade lasers. The technical approach involves using low Al-composition, non-polar nitride heterostructures (AlInGaN/GaN) grown on high quality free-standing m-plane GaN substrates to mitigate material quality and design issues that have, so far, impeded progress of nitride intersubband devices. The choice of polarization-free m-plane heterostructures has the tremendous advantage of eliminating the effect of built-in electric fields at hetero-interfaces. The research effort is interdisciplinary in nature and involves material design and growth, structural and optical material characterization, waveguide design and fabrication, and finally device testing.This research will enable a novel compact, coherent, tunable THz light source with power output suitable for technological applications (milliwatt level). In addition to broader wavelength flexibility, the THz nitride lasers are expected to have superior performance in terms of operating temperature and efficiency at the longer wavelengths currently accessible with GaAs THz quantum cascade lasers. The research focuses on THz lasers using non-polar nitrides, but the knowledge acquired is also relevant to nitride optoelectronic devices operating in other spectral ranges such as the near-infrared (telecom) range. Moreover, the acquired knowledge is valuable for other types of devices, such as transistors, and to other material systems. This research program also brings about important contributions to the physics of optical transitions and vertical charge transport in nitride materials. Elaborate modeling tools and techniques are developed to predict and explain real device behavior. Moreover, this project considerably advances knowledge regarding molecular beam epitaxy of III-nitride materials with the atomic-layer precision and exact reproducibility necessary for complex infrared devices.

标题：利用无偏振氮化物半导体用于传感和成像的新型紧凑型太赫兹激光器非技术描述：该项目研究一种新型紧凑型、高效的激光光源，工作在红外和微波范围之间的长波长光谱范围内，称为太赫兹(THz)间隙。由于常用半导体的基本限制，目前任何其他半导体激光器都无法达到这一范围。这个项目利用了氮化物半导体的独特性质。然而，氮化物也面临着一些与其原子结构和内置电场有关的独特挑战。为了克服这些挑战，研究人员使用复杂的建模工具来设计新的激光结构。然后使用分子束外延生长材料，这是一种允许在纳米级控制氮化物厚度的技术，并通过结构和光学技术进行表征。最后，制作并测试了激光器件，以研究它们在不同工作条件下的性能，并进一步完善设计参数。这些新型激光器具有影响许多技术应用的潜力，具有广泛的社会效益。这些应用大致分为两大类：太赫兹光谱学和太赫兹成像。太赫兹光谱学目前被用于从天文学、大气科学到等离子体聚变诊断和生化武器检测等领域。从机场安检到医学成像，太赫兹成像有着广泛的应用。该研究项目还为普渡大学的不同学生群体提供了独特的跨学科研究机会。特别注意向代表性不足的学生，特别是女性，提供实际的研究经验。外展活动将提高印第安纳州中部经济困难背景的7-12年级学生和教师对光子学的科学内容和方法的认识和接触。技术描述：该项目开发和研究一类新的远红外半导体发射器，适用于1-10太赫兹范围，特别是在砷化镓(30-40微米波长)的剩余辐射波段工作。这些激光器利用了非极性III-氮化物异质结导带中的子带跃迁，并采用了量子级联激光器的一般工作原理。该技术方法包括使用在高质量独立m平面GaN衬底上生长的低Al组分、非极性氮化物异质结(AlInGaN/GaN)，以缓解迄今为止阻碍氮化物亚带间器件发展的材料质量和设计问题。选择无偏振的m平面异质结具有消除异质界面上内置电场的影响的巨大优势。这项研究工作是跨学科的，涉及材料设计和生长，结构和光学材料表征，波导设计和制造，最后是器件测试。这项研究将实现一种新型的紧凑、相干、可调的太赫兹光源，其功率输出适合于技术应用(毫瓦级)。除了更宽的波长灵活性外，THz氮化物激光器预计将在工作温度和效率方面具有卓越的性能，目前使用的波长更长，可与GaAs太赫兹量子级联激光器一起使用。研究的重点是使用非极性氮化物的太赫兹激光器，但所获得的知识也与工作在其他光谱范围(如近红外(电信)范围)的氮化物光电设备有关。此外，获得的知识对其他类型的器件，如晶体管，以及其他材料系统也是有价值的。该研究项目还为氮化物材料的光学跃迁和垂直电荷输运的物理研究带来了重要的贡献。开发了复杂的建模工具和技术来预测和解释真实的设备行为。此外，该项目极大地提高了关于III-氮化物材料的分子束外延的知识，具有复杂红外设备所需的原子层精度和精确的重复性。