1. School
of Electronic Engineering, Bangor University, Bangor LL57 1UT, United Kingdom
2. Department
of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, United States
3. School of Materials Science & Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
4. Material
Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
5. Polymer Institute, Slovak Academy of Sciences, Bratislava 84541, Slovak Republic