III-Nitride LED Structures on Sidewall Grown Semipolar Facets

技术描述：本研究项目的重点是开发和理解用于发光二极管（LED）应用的半极性iii -氮化物结构的新方法。该方法基于c平面GaN模板的条纹图像化和深槽蚀刻，然后在侧壁重新生长形成半极面，在其上生长InGaN/GaN量子阱。主要的横向生长模式预计会导致位错密度显著降低。基于半极性材料的LED将受益于减少极化诱导场和增加铟的掺入，并且被认为是解决氮化LED技术中“绿隙”问题的一个有希望的解决方案。通过多种结构和光学表征，研究了不同图像化方法的优先面形形成和位错减少，以及不同半极性面形的生长动力学；横向生长条件下不同方向的铟和掺杂元素掺入效率；不同半极性排列结构的应变和内部量子效率。非技术描述：从本研究项目中获得的知识对于建立低缺陷密度，具有成本效益的半极性排列InGaN/GaN量子阱结构的设计，以及指导蓝绿区域内量子效率提高的发光二极管的技术发展具有重要意义。这些研究活动利用了pi先前建立的国家和国际合作。该项目通过课程开发、客座讲座和研讨会，为研究生提供全面的、应用驱动的学术研究的培训。该项目旨在让妇女和未被充分代表的少数民族以及高中生参与并支持他们进行暑期科学研究。

Technical Description: This research project focuses on the development and understanding of a new approach for fabrication of semipolar III-nitride structures for light emitting diode (LED) applications. The method is based on stripe patterning of c-plane GaN templates and deep-groove etching, followed by sidewall re-growth to form semipolar facets on which InGaN/GaN quantum wells are grown. The dominant lateral growth modes are expected to result in a significantly reduced dislocation density. The LEDs based on the semipolar materials should benefit from a reduced polarization-induced field and enhanced indium incorporation, and are regarded as a promising solution of the "green gap" problem in the nitride LED technology. By employing a variety of structural and optical characterization, the research team studies the preferential faceting formation and dislocation reduction for different patterning methods as well as the growth kinetics for different semipolar facets; the indium and doping-element incorporation efficiency in different directions in lateral growth regimes; the strain and internal quantum efficiency in structures with different semipolar alignments.Non-technical Description: The knowledge gained from this research project can be of significant importance for establishing a design of low defect-density, cost-efficient InGaN/GaN quantum-well structures with semipolar alignment, and for guiding technological development of light emitting diodes with improved internal quantum efficiency in blue-green region. The research activities leverage the PIs' previously established national and international collaborations. The project provides training of graduate students by exposing them to comprehensive, application-motivated academic research through curriculum development, guest lectures and seminars. The project intends to involve and support women and underrepresented minorities, as well as high-school students conducting summer science research.