1. School of Electrical Engineering Ben-Gurion University of the Negev POB 653 Beer-Sheva 8410501 Israel
2. Institut de Microelectrònica de Barcelona (IMB-CNM CSIC) 08193 Bellaterra Catalonia Spain
3. Microfabrication and Exploratory Nanotechnology group International Iberian Nanotechnology Laboratory (INL) Braga 4715-330 Portugal
4. The Ilse-Katz Institute for Nanoscale Science and Technology Ben-Gurion University of the Negev POB 653 Beer-Sheva 8410501 Israel