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, SUNY at Buffalo, Amherst, New York 14260, United States
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
4. Naval Research Laboratory, Washington, DC 20375, United States