1. Department
of Electrical and Electronics Engineering, Department of Physics,
UNAM—Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
2. Department
of Physics, Abant Izzet Baysal University, Bolu 14280, Turkey
3. 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