1. Department
of Physics, and Department of Electrical and Electronics Engineering,
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, Nanyang Technological University, Singapore 639798, Singapore