1. Department of Physics; Akdeniz University; Antalya Turkey
2. Institute of Earth and Space Sciences; Anadolu University; Eskisehir Turkey
3. Department of Physics, Nanoboyut Research Laboratory; Anadolu University; Eskisehir Turkey
4. Department of Physics; Middle East Technical University; Ankara Turkey
5. Center for Solar Energy Research and Applications (GÜNAM); Middle East Technical University; Ankara Turkey