1. Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, Ohio 45433, USA
2. Department of Electrical and Computer Engineering, Micro and Nanotechnology Laboratory, University of Illinois-Urbana-Champaign, Urbana, Illinois 61801, USA
3. Department of Electrical and Computer Engineering, George Mason University, Fairfax, Virginia 22030, USA
4. Wyle Laboratories, Inc., 4200 Colonel Glenn Hwy, Beavercreek, Ohio 45431, USA
5. Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson AFB, Ohio 45433, USA
6. Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, D-12489 Berlin, Germany