Dr. Sun Huarui from the University of Bristol, at the invitation of Professor Ma Xiaohua of School of Advanced Materials and Nanotechnology, paid an academic visit to the University, and delivered a report entitled “Reliability of AlGaN/GaN HEMTs: Electrical and Thermal Challenges” to teachers and students of School of Advanced Materials and Nanotechnology and School of Microelectronics on the afternoon of December 27. Dr. Sun Huarui completed his undergraduate at Tsinghua University and Ph.D. at the University of Michigan (Ann Arbor). At present, he is engaged in the reliability research of nitride HEMT at the Center for Device Thermography and Reliability led by Professor Martin Kuball of University of Bristol. He has published many research papers in important journals such asPhysical Review Letters,Applied Physics Letters,IEEE Electric Device Letters, andJournal of Applied Physics, etc.

His report mainly includes two parts, i.e. the mechanism of HEMT failure location under off-state stress and the thermal management of GaN device on diamond substrate, which are the research hotspots of nitride HEMT devices at present. Dr. Sun’s latest experimental results show that the grid leakage of device under the off-state stress is mainly caused by the electrochemical mechanism. He also skillfully used multiple defects in a device for statistical analysis, rather than using many devices in the previously reliability statistical analysis. Dr. Sun characterized the thermal resistance of diamond / nitride interface by reflection spectrum. The results indicated that the power density of the device could be increased by 300% by using diamond as the substrate of nitride HEMT device. This is the latest and most important research progress in the “Near Junction Thermal Transfer Program” in the United States.

Dr. Sun’s meticulous research and simple explanation left a deep impression on teachers and students present. During the explanation, Professor Ma Xiaohua and other teachers and students exchanged views with Dr. Sun on the key mechanism and technical issues. After the seminar, Dr. Sun visited the State Key Discipline Laboratory of Wide Band-gap Semiconductor, and reached an agreement on further exchanges and cooperation with the University. This academic exchange has played an important role in promoting the research of nitride reliability in the University.