Exploiting Novel Device Structures for Deep Ultraviolet Emitters

利用深紫外发射器的新型器件结构

• 批准号: 1402886
• 负责人: Jingyu Lin
• 金额: $ 32.49万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1402886&HistoricalAwards=false
• 关键词: Exploiting; Novel; Device; Structures; Deep

Abstract Title: Exploiting Novel Device Structures for Deep Ultraviolet Emitters Development of chip-scale deep ultraviolet (DUV) light sources is required for a wide range of applications such as probing intrinsic fluorescence in a protein, medical equipment/personnel decontamination, and photocatalysis. The external quantum efficiency (EQE) of Light Emitting Diodes (LEDs) operating in the region around 250 nm is still quite low (below 3%). Currently, AlGaN semiconductors are default choice for the DUV light sources. The poor p-type conductivity of Al-rich AlGaN alloys is the major obstacle that limits the EQE of these devices. Significant advances in the EQE of DUV emitters will require the exploitation of disruptive device concepts. This project aims to explore DUV device structures that exploiting new p-type layer strategies to overcome the intrinsic problem of low p-type conductivity in Al-rich AlGaN. The proposed efforts would not only yield breakthroughs in methods for the fabrication of DUV light emitting diodes (LEDs) with improved EQE, but would also lead to technological advancements in novel photonic materials and devices for a range of applications. Through the involvement in the research, students will be trained in the areas of nano-fabrication techniques, material/device design and processing using the state-of-the-art experimental facilities. The project will provide junior researchers with opportunities to participate in conferences and workshops, and gain exposure to the real world applications of DUV photonic devices. Educational activities will also include the integration of undergraduates into research via senior design projects and required project lab courses. Outreach activities include having the PIs serve as mentors of the prestigious Clark Scholars to bring an appreciation of science and technology to highly gifted high school students from around the nation and to increase diversity in science and engineering. The proposed DUV emitter layer structure is based on hexagonal boron-nitride (hBN) and AlGaN heterostructure bandgap and doping engineering. By implementing the direct wide bandgap and highly conductive hBN p-type layer strategy in nitride DUV emitters, p-type conductivities and DUV transparency of the electron blocking layer and p-type contact layer will be dramatically increased. This will significantly improve the free hole injection and EQE, reduce the operating voltage and heat generation, and increase the device operating lifetime. Control over the p-type electrical resistivity and conductivity type of epitaxial h-BN films will be established by in-situ doping via MOCVD growth. DUV emitter structures incorporating p-type hBN will be grown on sapphire with thick AlN templates to reduce the dislocation density. Ohmic contacts processing including annealing conditions will be optimized. DUV LEDs will be fabricated and their I-V, L-I characteristics, and wall plug efficiency will be correlated with the device structures and fabrication processes.

摘要标题：开发深紫外发射器的新型器件结构 芯片级深紫外 (DUV) 光源的开发需要广泛的应用，例如探测蛋白质中的固有荧光、医疗设备/人员净化和光催化。在 250 nm 附近工作的发光二极管 (LED) 的外量子效率 (EQE) 仍然相当低（低于 3%）。目前，AlGaN 半导体是 DUV 光源的默认选择。富铝AlGaN合金的p型导电性差是限制这些器件EQE的主要障碍。 DUV 发射器 EQE 的重大进步需要利用颠覆性器件概念。该项目旨在探索 DUV 器件结构，利用新的 p 型层策略来克服富铝 AlGaN 中 p 型电导率低的固有问题。所提出的努力不仅将在具有改进的EQE的DUV发光二极管（LED）的制造方法上取得突破，而且还将导致用于一系列应用的新型光子材料和器件的技术进步。通过参与研究，学生将使用最先进的实验设施接受纳米制造技术、材料/设备设计和加工领域的培训。该项目将为初级研究人员提供参加会议和研讨会的机会，并接触深紫外光子器件的实际应用。教育活动还将包括通过高级设计项目和所需的项目实验室课程将本科生融入研究。 外展活动包括让 PI 担任著名的克拉克学者的导师，让全国各地的天才高中生了解科学和技术，并增加科学和工程的多样性。所提出的 DUV 发射极层结构基于六方氮化硼 (hBN) 和 AlGaN 异质结构带隙和掺杂工程。通过在氮化物 DUV 发射器中实施直接宽带隙和高导电 hBN p 型层策略，电子阻挡层和 p 型接触层的 p 型电导率和 DUV 透明度将显着提高。这将显着改善自由空穴注入和EQE，降低工作电压和发热，并延长器件的工作寿命。 对外延 h-BN 薄膜的 p 型电阻率和导电类型的控制将通过 MOCVD 生长的原位掺杂来建立。包含 p 型 hBN 的 DUV 发射极结构将在具有厚 AlN 模板的蓝宝石上生长，以降低位错密度。包括退火条件在内的欧姆接触加工将得到优化。将制造 DUV LED，其 I-V、L-I 特性和电插效率将与器件结构和制造工艺相关。