November 5
@
3:00 PM
–
4:00 PM
AlN – a New Platform for Electronics
Abstract:
AlN has been ardently pursued as one of the most promising ultra-wide bandgap semiconductors (UWBGs) after GaN and SiC as the industry has been expanding rapidly on the high-volume manufacturing of GaN and SiC based technologies, including 12-inch GaN-on-Si, 8-inch SiC substrates and processing foundries etc. AlN is CMOS compatible with high thermal conductivity, high acoustic velocity and a rich family of heterostructures. Recently, Sc-, B- and Y-doped AlN alloys have garnered tremendous interest for their ferroelectric behavior. In this talk, I will focus on findings in our journey to develop new electronic devices on AlN in the past two decades.
Wurtzite III-nitrides are well known as a family of polar semiconductors. When sandwiching a narrow gap III-nitride layer with wider gap barrier materials, one interface is characterized as the negative polarization charge interface while the other as the positive polarization charge interface. The polarization charges are fixed in space and emanating electric field while the entire material stack will do everything it can to minimize its total free energy due to the thermodynamic driving force. As a result, compensating charges can be generated: either mobile charge carriers including delocalized electrons and holes, or charged defect states that are localized in the real and energy space. If undesired defect formation is sufficiently suppressed in the heterostructure, mobile charge carriers will be generated and can be harvested for electronic applications. To this end, we succeeded in generating both mobile electrons and holes in thin GaN quantum well sandwiched by AlN. I will discuss how we generate and detect these mobile charges, and some demonstrated utilities in terms of fundamental understanding and practical applications.
Professor Grace Xing
Bio:
Huili Grace Xing is currently the Director of SUPREME – a SRC JUMP2.0 research center, the William L. Quackenbush Professor of Electrical and Computer Engineering, Materials Science and Engineering at Cornell University, and has recently served as the Associate Dean for Research & Graduate Studies of the College of Engineering.
She is a recipient of the AFOSR Young Investigator Award, NSF CAREER Award, ISCS Young Scientist Award, the Intel Outstanding Researcher Award, and the SIA/SRC University Researcher Award. She is a fellow of APS, IEEE & AAAS.
Xing received a B.S. in physics from Peking University, M.S. in Material Science from Lehigh University and Ph.D. in Electrical Engineering from University of California, Santa Barbara, respectively. She was a faculty member with the University of Notre Dame from 2004 to 2014. Her research focuses on development of III-V nitrides, 2-D crystals, oxide semiconductors, recently also multiferroics & magnetic materials: growth, electronic and optoelectronic devices, especially the interplay between material properties and device development for high performance devices, including RF/THz devices, tunnel field effect transistors, power electronics, DUV emitters and memories. Together with her colleague Debdeep Jena, they were the first to demonstrate distributed polarization doping (DPD), especially the p-type DPD in nitride semiconductors. This doping scheme is fundamentally different from impurity doping and modulation doping, thus dubbed as the 3rd generation of doping science by Xing. Polarization doping is particularly powerful in polar ultrawide bandgap semiconductors since it might be the only known method to achieve both n-type and p-type in an UWBG semiconductor with doping properties akin to shallow impurity dopants.
Xing has delivered 200+ invited talks and seminars, and has authored/co-authored 350+ journal papers including Nature journals, Physical Review Letters, Applied Physics Letters, Electron Device Letters, and 140+ conference proceeding publications in IEDM, ISPSD etc. Her h-index is 89 on google scholar.