1. Department of Electrical and Electronics Engineering, Nanotechnology Research Center (NANOTAM), Bilkent University, Ankara, Turkey
2. Nanotechnology Research Center (NANOTAM), Bilkent University, Ankara, Turkey
3. Nanotechnology Research Center, Bilkent University, Ankara, Turkey
4. Department of Electrical and Electronics Engineering, and Department of Physics, Nanotechnology Research Center (NANOTAM), Institute of Materials Science and Nanotechnology (UNAM), Bilkent University, Ankara, Turkey