[1] Univ Crete, FORTH, IESL, Heraklion 71110, Crete, Greece
[2] Univ Crete, Dept Phys, Microelect Res Grp, Heraklion 71110, Crete, Greece
[3] Univ Barcelona, Dept Elect, E-08028 Barcelona, Spain
[4] Univ Athens, Dept Phys, Zografos 15784, Greece
[5] Slovak Acad Sci, IEE, SK-84239 Bratislava, Slovakia
[6] AF Ioffe Physicotech Inst, St Petersburg 194021, Russia