1. Department of Electrical Engineering and
Computer Science, and Research Lab of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Building 36-575, Cambridge, Massachusetts 02139, United States
2. Department
of Electrical Engineering, Columbia University, New York, New York 10027, United States
3. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States