1. Department of Engineering Sciences, Abdullah Gul University, Kayseri 38080, Turkey
2. UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara 06800, Turkey
3. LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798, Singapore