[1] Univ Notre Dame, Dept Elect Engn, Ctr Nano Sci & Technol NDnano, Notre Dame, IN 46556 USA
[2] Italian Inst Technol, Ctr Biomol Nanotechnol, I-73010 Lecce, Italy
[3] Univ Arkansas, Nanotechnol Ctr, Little Rock, AR 72204 USA
[4] Univ Kiel, Inst Mat Sci, Chair Multicomponent Mat, D-24143 Kiel, Germany