SEMINAR 1. Title : Novel properties of graphene-based vertical-junction diodes and applications 2. Speaker : Suk-Ho Choi ( Dept. of Applied Physics, Kyung Hee University ) 3. Time : 16:00 – 17:00, Thursday, May 12, 2016 4. Place : e+ Lecture Hall (room 83188), 2nd Research Building, Sungkyunkwan University 5. Summary : Recently, various types of device structures have been reported by employing graphene and its hybrids, but it is still unclear which will be successfully the prototypes for practical applications. In this seminar, I report graphene-based vertical-junction tunneling diodes that were fabricated by chemical vapor deposition and chemical processes. One of the most important characteristics of the graphene tunneling junctions is the asymmetric rectifying behavior showing on/off ratio of 103 under bias voltages below ± 10 V without gating. The observed rectification results from the strongly-corrugated high-resistive interlayers, graphene quantum dots (GQDs), or silica nanoparticles/GQDs hybrid, sandwiched between the doped or pristine graphene sheets, which is actually a structure like metal-insulator-metal or metal-semiconductor-metal tunneling diode. These vertical-tunneling diodes show unique photodetector (PD) characteristics, which follow well what are expected from their band structure. I also report first fabrication of graphene/Si quantum dots (SQDs)-heterojunction tunneling diodes that work as PDs showing high performances very sensitive to the variations in size of SQDs as well as in doping concentration of graphene. The I-V measurements demonstrate that some of these tunneling diodes show temperature-dependent negative differential resistance, i.e., resonant-tunneling behaviors. 6 Background : Education Ph. D. in Physics, February 1987 KAIST, Seoul, Korea M. S. in Physics, February 1984 KAIST, Seoul, Korea B. S. in Physics, February 1981 Seoul National University, Seoul, Korea Work 2009–Present: Fellow Professor, Kyung Hee University 2015-Present: Editorial Board Member, Scientific Reports 2011-Present: Editorial Board Member, Journal of the Korean Physical Society 1991–Present: Assistant, Associate, and Full Professor, Kyung Hee University 2005–2006: Visiting Professor, Samsung Advanced Institute of Technology 1998–1999: Visiting Professor, Australian National University (ANU) 1989–1990: Guest Scientist, National Institute of Standards and Technology (NIST), USA 1987–1991: Senior Researcher, Korea Standards Research Institute 2013–Present: Vice Chair of 17th and 18th ISPSA (2014 and 2016) 2013–Present: Vice Chair in Semiconductor Physics Division, Korean Physical Society 7. Questions : (☏ 031-299-4115)