Unique optoelectronic applications of graphene

Huili (Grace) Xing, Ph.D.
University of Notre Dame

Abstract
Graphene, an atomically thin 2D crystal with zero bandgap, has been touted for many intriguing applications,
particularly for transparent touch screens and wearable electronics. Its optoelectronic properties are equally
noteworthy. IR photodetectors and modulators as well as THz emitters have been proposed and demonstrated
recently. As a standing alone 2DEG with tunable conductivity, we discovered it is possible to use graphene to
modulate THz beam transmission/reflect on from near unity to zero. The experimentally demonstrated graphene
THz modulators are already among the best electrically driven devices today. As the thinnest conductor on earth,
graphene has much lower density of states compared with conventional thin metal fi lms. Consequently, graphene
off ers unique solutions to various problems that have been historically hindered by the high DOS of metal thin
film. Recently, we observed, for the first time, hole injection from Si over the oxide barrier to graphene in internal
photoemission spectroscopy measurements, enabled by this properties of graphene. If time allows, I will also
review the recent development of GaN electronics and tunnel fi eld eff ect transistors (FETs), another two diff erent
topics, in our group.

Biography
Huili (Grace) Xing is currently the John Cardinal O’Hara CSC Associate Professor of Electrical Engineering at the
University of Notre Dame. She obtained B.S. in physics from Peking University (1996), M.S. in Material Science
from Lehigh University (1998) and Ph.D. in Electrical Engineering from University of California, Santa Barbara
(2003), respectively. Her research focuses on development of III-V nitride and 2-D crystal semiconductor growth
and (opto)electronic devices, especially the interplay between the material quality and device developments.
More recent research interests include THz applications. She is a recipient of AFOSR Young Investigator Award and
NSF CAREER Award.