1. Department of Engineering Sciences and Mathematics, Division of Materials Science, Luleå University of Technology, 97187 Luleå, Sweden
2. Institute for Microelectronics and Microsystems Section of Bologna, National Research Council, Via P. Gobetti, 101, I-40129 Bologna, Italy
3. Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, 30170 Venezia Mestre, Italy