1. LUMINOUS! Center of Excellence for Semiconductor Lighting
and Display, School of Electrical and Electronics Engineering, Division
of Physics and Applied Physics, School of Physical and Mathematical
Sciences, Nanyang Technological University, Singapore 639798, Singapore
2. Department of Physics, Department of Electrical
and Electronics Engineering, UNAM—National Nanotechnology Research
Center and Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
3. Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, United States