Reliability Study and Failure Analysis of Wide Bandgap GaN Vertical Power Devices: From Materials to Devices

摘要：电力电子设备是电力和能源系统的核心，广泛应用于电动/混合动力汽车、数据中心、电网、太阳能电池板和风力涡轮机等领域。据估计，到2030年，全球80%的电力将由电力设备处理。与现有的硅器件相比，垂直氮化镓（GaN）功率器件被广泛认为是下一代高效、紧凑和强大的电力电子器件的关键推动者，具有改变未来电力电子技术的潜力。尽管具有很高的潜力，但由于器件过早退化和失效，垂直GaN功率器件的性能仍然远远落后于其理论极限。关于垂直GaN功率器件的器件可靠性和失效机制的基本知识仍然很大程度上缺失，这严重阻碍了GaN功率电子器件的进一步发展和采用。本项目旨在促进对垂直GaN功率器件可靠性和故障的基本理解，并使用材料-器件协同设计方法将其性能推向GaN极限。该项目的成功成果将导致对垂直GaN功率器件在物理、材料和器件层面的变革性理解和新发展。通过跨学科的方法，包括材料生长和表征、器件设计和制造、可靠性测试和故障分析，将获得基本的新知识。该项目的智力优势包括对垂直GaN功率器件的退化和失效机制的新理解，GaN器件可靠性分析的新材料和器件表征工具集的开发，以及对垂直GaN功率器件的设计和制造的新见解，以充分发挥其潜力。为了产生更广泛的影响，该项目将为代表性不足的群体提供工程、材料和物理领域跨学科研究技能的劳动力培训，为K-12学生和教师整合教育活动，并促进半导体和电力电子领域的STEM本科研究。技术摘要：垂直氮化镓（GaN）功率器件具有材料缺陷密度低、不受表面相关退化和可靠性影响、雪崩能力强、芯片面积小、散热性能好等优点，是高压大功率电子应用的理想选择。尽管有这些优点，但目前的垂直GaN功率器件仍然存在过早失效的问题，其器件性能远远低于GaN材料的极限。对于垂直GaN器件的可靠性研究和失效分析的研究非常有限，缺乏基本的认识。本项目将直接解决这一研究和科学空白，获得垂直GaN功率器件失效模式和机理的基础知识。将采用跨学科的方法来实现材料-器件协同设计，包括失效地点的材料表征、缺陷工程、电流冲击事件下的可靠性研究和理论建模。该项目将促进对垂直GaN功率器件失效机制的基本理解，加速大功率鲁棒GaN器件的器件开发，并释放GaN材料在高效功率转换方面的全部潜力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract:Power electronic devices are at the heart of power and energy systems that are widely used in electric/hybrid vehicles, data centers, power grids, solar panels, and wind turbines. It is estimated that 80% of global electricity will be processed by power devices by 2030. Compared with the incumbent silicon devices, vertical gallium nitride (GaN) power devices are broadly regarded as key enablers for the next-generation efficient, compact, and robust power electronics, with the potential to transform future power electronics technologies. Despite the high potential, the performance of vertical GaN power devices still falls far behind their theoretical limit due to premature device degradation and failure. The fundamental knowledge on the device reliability and failure mechanisms of vertical GaN power devices is still largely missing, which significantly hinders the further development and adoption of GaN power electronics. This project aims to advance the fundamental understanding on the reliability and failure of vertical GaN power devices, and use a material-device co-design approach to push their performance to GaN limit. Successful outcomes of the project will lead to transformative understanding and new development of vertical GaN power devices at physics, materials, and devices levels. And fundamental new knowledge will be achieved using an interdisciplinary approach involving materials growth and characterization, device design and fabrication, and reliability testing and failure analysis. The intellectual merits of the project include new understandings on the degradation and failure mechanisms of vertical GaN power devices, the development of new material and device characterization toolsets for the GaN device’s reliability analysis, as well as new insights into the design and fabrication of vertical GaN power devices to realize their full potential. To achieve broader impacts, the project will provide workforce training for underrepresented groups with interdisciplinary research skills in engineering, materials, and physics, integrate educational activities for K-12 students and teachers, and promote STEM undergraduate research in semiconductors and power electronics.Technical Abstract:Vertical gallium nitride (GaN) power devices are ideal candidates for high-voltage high-power electronic applications due to their advantages, such as lower materials defect density, immunity to surface-related degradation and reliability concerns, and avalanche capability, as well as smaller chip areas and better heat dissipation. Despite these advantages, the current vertical GaN power devices still suffer from premature failure, and their device performance is far below the GaN material limit. There are very limited research efforts on the reliability study and failure analysis of vertical GaN devices, and the fundamental understandings are still missing. This project will directly address this research and scientific gap and obtain fundamental knowledge on the failure modes and mechanisms of vertical GaN power devices. An interdisciplinary approach will be used to achieve material-device co-design, including materials characterizations at failure sites, defects engineering, reliability study under current surge events, and theoretical modeling. This project will advance the fundamental understanding on the failure mechanisms of vertical GaN power devices, accelerate the device development of high-power robust GaN devices, and unlock the full potential of the GaN materials for efficient power conversions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.