A Path Towards III-Nitrides-Based Superjunction Devices

各种传统和可再生能源应用对大功率开关的需求呈指数级增长。拟议的研究将为电力电子提供一种变革性和颠覆性的技术，该技术将远远超出经典半导体材料的限制，并导致前所未有的开关功率密度和超出硅基技术的可靠性。这种颠覆性技术的成功演示将彻底改变能量转换和传输、能量存储以及在电动机驱动和其他功率密集型应用中的相关应用。这项研究将对材料和设备产生直接影响，这些材料和设备将用于处理保护和扩展自然资源的应用，通过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废水。该项目将为培养具有创新思维的下一代工程师提供机会，并将支持一名博士生、一名兼职本科生助理和一名博士后研究员。在该项目中开发的新概念将在教育和推广工作中实施，特别是将特性和过程控制方案整合到处理可持续性，保护和扩展自然资源所需材料的应用中。目前基于氮化镓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二极管上。需要新的技术突破，不受经典材料的优点的限制。超结是一种横向器件，通过在反向偏置下获得完全补偿和在正向偏置下获得非常低的导通电阻，从而超越了材料的性能限制，即它们在一个方向上表现为介电体，而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，还没有在宽带隙材料中尝试过超结。最近在侧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，并为氮化镓基超结技术提供了一条新的途径，该技术不依赖于再生长和离子注入技术，这些技术在iii -氮化物中一直不成功，尽管它们通常用于Si技术。这些器件最终将允许显著击穿电压超过5千伏和低导通电阻。本研究将建立垂直n型和p型厚漂移区结的生长技术，该技术基于n极性和ga极性GaN畴的可控同时生长，相关的低掺杂水平在10'16到10'17 cm-3范围内，可以完全耗尽。在p-和n-掺杂区域中生长和控制掺杂的能力将为超结器件结构的设计建立一条途径，并证明击穿电压超过1200v的超结性能比Baliga的优点值预测的要好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，其架构不受传统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.