Semiconductor Nano- And Micro-Structures Grown On Two-Dimensional Nanomaterial

Date(s):

Location:
Jacobs Hall, Room 2512, Jacobs School of Engineering, 9500 Gilman Dr, La Jolla, San Diego, California 92093

Sponsored By:
Professor Shadi Dayeh

Speaker(s):
Gyu-Chul Yi
Department of Physics
Seoul National University
Gyu-Chul Yi

Abstract:

Contemporary human life relies heavily on mobile devices such as smart-phone, lap-top, or tablet PC which process tremendous amount of information every day. In near future, rapid development of information technology (IT) would eventually integrate the devices as a wearable and flexible form that will collect and process information ubiquitously. Organic materials and amorphous films have long been studied for the foldable and wearable devices since the devices must be fabricated on a flexible plastic film. However, single-crystalline inorganic semiconductors can provide many advantages over organic materials for optoelectronic and electrical device applications, including high carrier mobility and radiative recombination rates, as well as long-term stability and reliability. Nevertheless, problems associated with high-quality inorganic film growth on flexible substrates represent one of the major obstacles to the use of inorganic semiconductors in flexible and stretchable devices. Previous techniques such as epitaxial growth and lift-off circumvent this problem by separation of the thin film from the growth substrates but difficulty in separating the film from a single-crystal limits their use. Meanwhile, the layered structure of 2-dimentional (2-D) nanomaterials, which consist of weakly bonded layers, makes it easy to transfer the film to foreign substrates. Accordingly, hybrid heterostructures composed of high-quality inorganic thin films or nanostructures grown directly on graphene offer a novel material system for transferable and/or flexible optoelectronics [1,2]. Here I will present controlled growths of ZnO and GaN nano- and micro-structures on 2D nanomaterials using catalyst-free metal-organic vapor phase epitaxy and describe the methods to fabricate flexible LEDs and transistors using the hybrid nanostructures.

Speaker Bio:
“Gyu-Chul Yi”, Ph.D. has been a professor in the Department of Physics at Seoul National University since 2009. Before joining in Seoul National University, “Yi” was an assistant and associate professor since 1999 and also the Chong Yul Lee Chair professor since 2004 at POSTECH. ”Yi” received his B.S and M.S degrees in physics from Seoul National University, Korea in 1990 and 1992, respectively, and his Ph.D degree from Northwestern University, Evanston, IL., in 1997. Then he worked as a post-doctoral research fellow at Oak Ridge National Laboratory, Oak Ridge, TNfrom 1997 to 1999. He was a director of National Creative Research Initiative Center for Semiconductor Nanostructures from 2004 to 2013 and is currently a leader of Global Research Laboratory supported by National Research Foundation in Korea. He received several prestigious prizes of Song-gok Scientist Prize (2006), President (1st) prize in Korean Innovation and Patent contest (2006), Year of POSTECH Research Award (2007), Gold Prize in the 35th International Invention (Geneve, Switzerland) (2008), and SNU Creative and Interdisciplinary Researcher Award (2013). He has published more than 250 articles in various international SCI journals including Science, Advanced Materials, Nano Letters and Applied Physics Letters. He developed catalyst-free metal-organic chemical vapor deposition to grow high quality one-dimensional nanomaterials and fabricated micro-LEDs using the nanomaterials. Furthermore he created hybrid-dimensional nanomaterials by growing ZnO nanostructures and GaN films on graphene and h-BN for transferable optoelectronic and electrical devices. His papers have been cited more than 10,000 in total and his h-index is 58 (Google Scholar) and 48 (Web of Science).

Contact:
Cheryle Wills (clwills@ece.ucsd.edu)