A Path Towards III-Nitrides-Based Superjunction Devices

各种传统和可再生能源应用对高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，远远超出传统半导体材料的限制，并带来前所未有的开关功率密度和可靠性，超越硅基技术。这种颠覆性技术的成功演示将彻底改变能源转换和传输、能源存储以及电机驱动和其他电力密集型应用中的相关应用。这项研究将直接影响材料和设备，这些材料和设备将用于处理自然资源的保护和扩展，通过有效利用和传输电能，通过使用紫外线消毒提供清洁的饮用水，以及检测污染物和其他流出物。该计划将提供机会，教育下一代工程师能够开箱即用的思维，并将支持一名博士生，兼职本科助理和博士后研究员。该项目中开发的新概念将在教育和推广工作中实施，特别是将表征和过程控制计划整合到处理可持续性，保护和扩展我们自然资源所需材料的应用中。当前GaN基功率器件设计集中于简单的肖特基和p-i-n二极管。需要新的技术突破，不受经典材料优值的限制。超结是横向器件，其通过在反向偏置下获得完全补偿并且在正向偏置下获得非常低的导通电阻而超过材料品质因数极限，即，它们在一个方向上表现为导体，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，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。在横向极性结构的生长和新开发的掺杂控制方案中的最新技术进步弥补了缺失的技术差距，并为不依赖于再生长和离子注入技术的GaN基超结技术提供了新的途径，所述再生长和离子注入技术在III族氮化物中是不成功的，尽管它们常规地用于Si技术中。这些器件最终将允许超过5 kV的显著击穿电压和低导通电阻。本研究将建立基于N-极性和Ga-极性GaN畴的可控、同时生长的垂直n型和p型厚漂移区结的生长技术，其中相关的低掺杂水平在10'16至10'17 cm-3的范围内以用于完全耗尽。在p型和n型掺杂域中并排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，并证明超结的击穿电压超过1200 V，性能比Baliga的品质因数预测的好500%。此外，这项研究将为新一代设备提供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.