1. Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 10, 01069 Dresden, Germany
2. Institute of Solid State Physics, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena, Germany
3. Department of Chemistry, Hamilton Hall, University of Nebraska−Lincoln, 639 North 12th Street, Lincoln, Nebraska 68588, United States
4. Terahertz Materials Analysis Center (THeMAC), Department of Physics, Chemistry and Biology, IFM, Linköping University, Linköping S-58183, Sweden
5. Centre for III-Nitride Technology (C3NiT), Department of Physics, Chemistry and Biology, IFM, Linköping University, Linköping S-58183, Sweden
6. Physics Department and Hamdi Mango Center for Scientific Research, University of Jordan, Amman 11942, Jordan
7. Heliatek GmbH, Treidlerstr. 3, Dresden 01139, Germany