电子科学与技术学院2017年学术报告会之三- High-performance Vertical Gallium Nitride
来源：电子科学与技术学院 浏览：39 时间：2017-03-20
题目：High-performance Vertical Gallium Nitride (GaN) Diodes and Transistors for Power Electronics
报告人：Yuhao Zhang（张宇昊）, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, USA
A new generation of power electronics based on wide bandgap semiconductors is expected to significantly reduce the losses in power conversion circuits and, at the same time, change the form factor of power systems through a significant increase in the power density. Overall, energy savings greater than 10% of the world’s energy consumption could be possible. In particular, Gallium nitride (GaN) devices are very exciting candidates for next-generation power electronics, for the applications in electrical vehicles, data centers, high-power and high-frequency communications (e.g. 5G, satellites broadcasting, etc.).
Currently, both lateral and vertical structures are considered for GaN power devices. Compared to the extensively-studied lateral GaN devices, vertical GaN power devices have attracted increased attention recently, due to the potential for high breakdown voltage and current without enlarging the chip size as well as superior thermal performance. In this talk, I will describe my work on developing a new generation of vertical GaN diodes and vertical FETs that addresses the challenges of conventional GaN devices.
The commercialization of vertical GaN power devices has been hindered by the high cost of bulk GaN. In 2014, I demonstrated for the first time the feasibility of using vertical devices grown on a silicon (Si) substrate. In 2016, 500-V level high-performance GaN vertical pn diodes on Si substrate are also demonstrated, with high forward current, low leakage current, and high-temperature operation at 300 oC.
In 2016-2017, I also developed several novel Schottky diode structures consisting of trench MIS structures, field rings, and implanted pn structures. These new structures greatly enhanced the reverse blocking characteristics (104-fold lower off-state current and 600-800 V breakdown voltage) while maintaining a Schttky-like good forward conduction. Besides, I also contributed to developing a normally-off vertical FET structure without the need for p-doped GaN layers or material regrowth.
At the end, I will briefly discuss the prospects of emerging power devices based on other wide-bandgap materials,e.g.diamond,alimium nitride gallium oxide, and introduce my work on GaN-diamond intergrated devices.
Yuhao Zhang is a Ph. D.candidate working with Professor Tomas Palacios in the Department of EECS at Massachusetts Insitute of Technology,and will graduate in this June. He is interested in novel wide-bandgap semiconductor devices for power electronics and mm-Wave switching.He received his B.S.from Peking University in physics in2011,and an M.S.from Massachusetts Institute of Technology in electrical engineering in 2013.
During his graduate research,he has published over 10 first-authored papers in top journals and conferences,including two first-authored papers in Proceedings of IEEE International Electron Meetings (IEDM). Besides,he has also made over 10 presentations or invited talks in international conferences,and has 6 pending or issued U.S.patents.