1. Center of Materials Technology & Photonics and Electrical Engineering Department, School of Engineering, Technological Educational Institute (TEI) of Crete, Heraklion, 71004 Crete, Greece
2. Department
of Materials Science and Technology, University of Crete, Heraklion, 71003 Crete, Greece
3. Physics
and Astronomy, Faculty of Physical Sciences and Engineering, University of Southampton, Southampton, SO171BJ, United Kingdom
4. Institute
of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion, 711 10 Crete, Greece