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

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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.