AlGaN/GaN high-electron-mobility transistors (HEMTs) have high saturation velocity, high mobility, and high current density with high breakdown electric field, which make them promising for next-generation high power and high frequency device applications. However, AlGaN/GaN HEMTs always demonstrate normally-on operation, which is not desirable for Electrical vehicle applications due to safety concerns. To achieve normally-off operation for GaN HEMT device, several methods have been proposed to achieve high positive threshold voltage. For example, p-GaN, recessed-gate, and fluorine treated AlGaN technologies have been demonstrated. In this work, a new charge storage structure with hybrid ferroelectric charge-trapping gate stack is used to realize the GaN E-mode MIS-HEMT for power switching applications. This gate stack structure combines ferroelectric film with charge-trapping layer and current blocking film, resulting in a polarization charge field against the applied gate voltage, and thus achieves a large positive shift of the threshold voltage. As a result, the device has a high Vth, meanwhile maintain low on Resistance, high I_(DS,MAX), and high breakdown voltage are maintained, perfect for EV applications.

 Professor Edward Yi Chang received his PhD degree from the University of Minnesota, Minneapolis, MN, USA, in 1985 and honorable doctorate for UKM Malaysia. and worked for Unisys Corp and Comsat Labs in the USA from 1985-1992. In 1992, he joined National Chiao Tung University (NCTU), Hsinchu, Taiwan. He is currently Chair professor of National Yang Ming Chiao Tung University (NYCU), Dean of International College of Semiconductor Technology, and Chair Professor of the Department of Materials Science and Engineering and Department of Electronics Engineering. Prof. Chang is an IEEE Life Fellow, JSAP Fellow International, TMRS Fellow and Distinguished Lecturer of the IEEE Electron Devices Society.     His current research interests include III-V and GaN based devices for logic, high frequency, and power applications. Dr. Chang holds more than 40 patents worldwide and has authored or co-authored more than 250 journal papers in related research areas.