1. Research Group “Solid
State Lighting”, NanoEnergieTechnikZentrum, University Duisburg-Essen, 47057 Duisburg, Germany
2. Werkstoffe
der Elektrotechnik and CENIDE, University Duisburg-Essen, 47057 Duisburg, Germany
3. Department of Electrical
and Electronics Engineering, Department of Physics, UNAM−Institute
of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
4. 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