1. Nanotechnology Research Center and the Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey
2. Nanotechnology Research Center, Bilkent University, Ankara, Turkey
3. Department of Electrical and Computer Engineering, University of Michigan, Ann Arbor, MI, USA
4. Nanotechnology Research Center, the Department of Electrical and Electronics Engineering, the Department of Physics, and the Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey