Collaborative Research: ECCS-EPSRC: Nitride Super-Junction HEMTs for Robust, Efficient, Fast Power Switching

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Award AbstractProposal Number: 2036740 & 2036915Principal Investigator: Yuhao Zhang and Han Wang (co-PI)Title: Collaborative Research: ECCS-EPSRC: Nitride Super-Junction HEMTs for Robust, Efficient, Fast Power SwitchingInstitution: Virginia Polytechnic Institute and State University (Lead) and University of Southern CaliforniaNon-Technical Abstract:Power semiconductor devices are regularly utilized as solid-state switches in power electronic systems that are widely used in consumer electronics, data centers, electric vehicles, electricity grid, and renewable energy systems. The global power device market exceeds $15 billion in 2019 and is fast growing. Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) are commonly perceived as the next generation of power devices. Despite their initial commercialization recently, their wide adoption in industrial applications is hindered by the limitation in reliability and robustness, resulting in considerable over design, rendering device performance far below the material limit. This project will develop a new generation of robust, charge-balanced GaN HEMTs through innovation in the semiconductor materials and device structure. Interdisciplinary research will be carried out in materials, devices, fabrication processes, and circuit-level tests through collaboration between Virginia Tech and the University of Southern California in the United States, as well as University of Cambridge in United Kingdom under the “NSF Engineering - UKRI Engineering and Physical Sciences Research Council Lead Agency Opportunity (ENG-EPSRC)”. This US-UK collaborative project provides opportunities for student education and international exchange, development of cross-university teaching modules, and industrial collaboration for potential technology transfer. This interdisciplinary, cross-continent project also involves outreach activities for K-12 students and teachers, and promotes educational activities related to microelectronics and power electronics technologies.Technical Abstract:This overarching hypothesis is that robust gallium nitride (GaN) high-electron-mobility transistors (HEMTs) can be implemented by selective-area, nearly defect-free embedding of p-type regions into the two-dimensional electron gas (2DEG) channel, forming a novel charge-balanced super-junction structure. This novel 2D-3D super-junction structure can not only enhance the device robustness by managing the electric field and avalanche capability, but also allow significantly higher 2DEG density while maintaining the normally-off operation, thereby decreasing the device specific on-resistance and boosting its switching frequency. Despite these promises, major gaps exist in the device physics of the novel super-junction, interfacial material properties, and the dynamic performance of super-junction HEMTs in power electronic circuits. Funded by the “NSF Engineering - UKRI Engineering and Physical Sciences Research Council Lead Agency Opportunity (ENG-EPSRC)”, this project aims to address the scientific knowledge gaps in four relevant areas through the US-UK research collaboration: (a) to explore the design space and performance limits of the novel super-junction HEMT device; (b) to probe new methods of selectively introducing p-type dopants into the 2DEG channel to realize the super-junction functionality; (c) to develop an in-depth understanding of the dopant profiles, carrier transport, and trap dynamics in the nitride super-junction structure; and (d) to correlate the nano/mesoscale materials and interface properties with the dynamic characteristics and robustness of GaN HEMTs.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.