1. Department of Microelectronics, Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems; National Centre for Scientific Research “Demokritos”, P.O. Box 60228; Aghia Paraskevi 15310 Athens Greece
2. CEMES-CNRS et Université de Toulouse; nMat group, BP 94347; 31055 Toulouse Cedex 4 France
3. Nano-MicroElectronics Research Group (NMRG); IESL-FORTH, P.O. Box 1527; 71110 Heraklion Greece
4. Physics Department; University of Crete, P.O. Box 2208; 71003 Heraklion Greece