1. Department
of Nanoenergy Engineering and College of Nanoscience and Nanotechnology, Pusan National University, Busan 46241, Republic of Korea
2. Device & System Research Center, Samsung Advanced Institute of Technology, Samsung Electronics, Suwon 16676, Republic of Korea
3. Physik-Department
ECS, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany
4. Department
of Materials Science and Engineering, Frederick Seitz Materials Research
Laboratory, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States