1. Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
2. Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Science and Nanotechnology, Nanyang Technological University, Singapore 639798, Singapore
3. Department of Materials Science and Engineering, Faculty of Engineering, Anadolu University, 26555 Eskisehir, Turkey
4. Department of Physics, Abant Izzet Baysal University, Bolu 14030, Turkey
5. Department of Electrical and Electronics Engineering, Faculty of Engineering, Anadolu University, 26555 Eskisehir, Turkey