1. Materials Science and Engineering
Division, Material Measurement
Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
2. Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland 20742, United States
3. Institute
for Research in Electronics and Applied Physics, University of Maryland, College
Park, Maryland 20742, United States
4. Semiconductor and Dimensional
Metrology Division, Physical
Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States