Selami Palaz 2, Husnu Koc 3, Gokay Ugur 4, Ekmel Ozbay 1, Amirullah Mamedov 1
1 Bilkent University, Nanotechnology Research Center, Ankara, Turkey, 2 Department of Physics, Harran University, URFA, Turkey, 3 Department of Physics, Siirt University, SIIRT, Turkey, 4 Department of Physics, Gazi University, ANKARA, Turkey