A Path Towards III-Nitrides-Based Superjunction Devices

用于各种经典和可再生能源应用的大功率开关的需求呈指数级增长。这项拟议的研究将为电力电子提供一种革命性和颠覆性的技术，这种技术将远远超出传统半导体材料的限制，并导致前所未有的开关功率密度和可靠性超过硅基技术。这种颠覆性技术的成功展示将彻底改变电动马达驱动和其他电力密集型应用中的能量切换和传输、能量存储以及相关应用。这项研究将对用于保护和扩展自然资源的应用的材料和设备产生直接影响，因为它允许有效利用和传输电能，通过使用紫外线消毒获得清洁饮用水，以及检测污染物和其他流出物。该项目将提供培养具有开箱即用思维能力的下一代工程师的机会，并将支持一名博士生、一名兼职本科生助理和博士后研究员。在这一项目中形成的新概念将在教育和外联工作中得到落实，特别是将定性和过程控制计划纳入处理我国自然资源可持续性、保存和扩展所需材料的应用。目前基于GaN的功率器件设计主要集中在简单的肖特基二极管和p-i-n二极管。需要新的技术突破，不受经典材料优劣系数的限制。超结是一种横向器件，它在反向偏置下获得完全补偿，在正向偏置下获得非常低的导通电阻，从而超过材料的品质因数限制，即它们在一个方向上表现为介质，在另一个方向上表现为导体。虽然硅基超结是一种成熟的技术，被称为CoolMos，但由于特殊的技术挑战，还没有人尝试在宽带隙材料中进行超结。最近在横向极性结构生长方面的技术进步和新开发的掺杂控制方案弥补了缺失的技术差距，并为不依赖再生长和离子注入技术的GaN超结技术提供了一条新的途径，这些技术在III-氮化物中一直未获成功，尽管它们通常用于Si技术。这些器件最终将允许显著的击穿电压超过5千伏和低导通电阻。这项研究将建立垂直n型和p型厚漂移区结的生长技术，该技术基于N极和Ga极GaN磁区的可控同时生长，相关的低掺杂水平在10‘16到10’17厘米-3范围内，以实现完全耗尽。这种同时生长和控制掺磷和掺氮的能力将为超结器件结构的设计开辟一条道路，并展示击穿电压超过1200V的超结，其性能比Bilia的优值系数预测的高出500%。此外，这项研究将为新一代设备提供一种变革性和颠覆性的技术，其架构不受经典增长和处理方法的限制。

The demand for high power switches for various classical and renewable energy applications is increasing exponentially. The proposed research will provide for a transformative and disruptive technology for power electronics that will go well beyond classical semiconductor materials limits and lead to unprecedented switching power densities and reliability beyond the Si-based technology. The successful demonstration of such disruptive technology would revolutionize energy switching and transmission, energy storage, and related applications in electrical motor drives and other power-intensive applications. This research will have a direct impact on the materials and devices that will be used for applications that deal with the preservation and extension of natural resources by allowing for an efficient use and transmission of electrical energy, availability of clean potable water through disinfection by the use of UV, and the detection of pollutants and other effluents. This program will provide the opportunity to educate the next generation of engineers capable of out-of-the-box thinking and will support one PhD student, and a part-time undergraduate assistant and post-doctoral researcher. The novel concepts developed within this project will be implemented in the educational and outreach efforts, especially integrating characterization and process control schemes to applications dealing with materials needed for sustainability, preservation and extension of our natural resources. Current GaN-based power device designs focus on simple Schottky and p-i-n diodes. New technological breakthroughs are needed that are not limited by the classical materials figure of merit. Superjunctions are lateral devices that surpass the materials figure of merit limit by attaining full compensation under the reverse bias and very low on-resistance under the forward bias, i.e., they behave as dielectrics in one direction and as conductors in the other. Although Si-based superjunctions are a mature technology, known as CoolMos, no superjunctions have been attempted in wide bandgap materials because of the exceptional technological challenges. Recent technological advances in the growth of lateral polar structures and newly developed doping control schemes bridge the missing technological gap and provide a new path for GaN-based superjunction technology that does not rely on re-growth and ion implantation technologies, which have been unsuccessful in III-nitrides although they are routinely used in the Si technology. These devices will eventually allow for significant breakdown voltages exceeding 5 kV and low on-resistance. This research will establish growth technology for both, vertical n-type and p-type thick drift region junctions based on controllable, simultaneous growth of N-polar and Ga-polar GaN domains, with the associated low doping levels in the range of 10'16 to 10'17 cm-3 for complete depletion. The ability to grow and to control doping in p- and n-doped domains side-by-side will establish a pathway for the design of superjunction device structures and demonstrate superjunctions with breakdown voltages exceeding 1200 V and 500% better performance than predicted by the Baliga's figure of merit. Furthermore, this research will provide a transformative and disruptive technology for a new generation of devices whose architecture is not limited by the classical growth and processing approaches.