III-Nitride LED Structures on Sidewall Grown Semipolar Facets

技术说明：该研究项目的重点是开发和理解一种新的方法，用于制造发光二极管（LED）应用的半极性III族氮化物结构。该方法是基于条纹图案化的c-平面GaN模板和深槽蚀刻，然后通过侧壁再生长，以形成半极性刻面上生长InGaN/GaN量子威尔斯。预计占主导地位的横向生长模式将导致位错密度显著降低。基于半极性材料的LED将受益于降低的极化诱导场和增强的铟掺入，并且被认为是氮化物LED技术中的“绿色间隙”问题的有希望的解决方案。通过采用各种结构和光学表征，研究团队研究了不同图案化方法的优先小面形成和位错减少，以及不同半极性小面的生长动力学;横向生长机制中不同方向上的铟和掺杂元素掺入效率;具有不同半极性排列的结构中的应变和内部量子效率。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取向InGaN/GaN量子阱结构的设计以及指导具有改善的蓝绿色区域内量子效率的发光二极管的技术开发具有重要意义。研究活动利用PI先前建立的国家和国际合作。该项目通过课程编制、客座讲座和研讨会，使研究生接触全面的、以应用为目的的学术研究，从而对研究生进行培训。该项目旨在让妇女和代表性不足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.