1. Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas (FORTH), N. Plastira 100, Heraklion, Crete 71110, Greece
2. Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110, Greece
3. Department of Materials Science and Technology, University of Crete, Heraklion, Crete 70013, Greece
4. Department of Materials, University of Manchester, Manchester M13 9PL, United Kingdom
5. National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
6. Department of Physics, University of Crete, Heraklion, Crete 70013, Greece
7. Henry Royce Institute for Advanced Materials, University of Manchester, Manchester M13 9PL, United Kingdom
8. Institute of Materials Science and Computing, University Research Center of Ioannina (URCI), Ioannina 45110, Greece
9. Science Program, Texas A&M University at Qatar, P.O. Box 23874, Doha, Qatar