1. Electronics
Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC 20375, United States
2. National
Research Council, U.S. Naval Research Laboratory, Washington, DC 20375, United States
3. Material
Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC 20375, United States
4. Department
of Physics and Astronomy, Howard University, Washington, DC 20059, United States
5. Department
of Electrical and Computer Engineering, and the Beckman Institute
for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States