1. IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, United States
2. The Department of Electrical Engineering, The Department of Materials Science & Engineering, and The Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
3. Micro/Nano Technology Department, Space Materials Laboratory, The Aerospace Corporation, Los Angeles, California 90009, United States
4. Device Solutions Business, Samsung Electronics Co., Korea
5. Materials Engineering and Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, St Lucia, Queensland 4072, Australia.