1. Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
2. Department of Electrical Engineering and Computer Science, Syracuse University, Syracuse, New York 13244, United States
3. Institute for Research in Electronics and Applied Physics (IREAP), University of Maryland, College Park, Maryland 20742, United States
4. Ceramics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
5. Surface and Microanalysis Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States