1. Department of Electrical and Computer Engineering, University of Nebraska–Lincoln, Lincoln, Nebraska 68588, USA
2. Terahertz Materials Analysis Center and Center for III-N Technology (C3NiT)—Janzèn, Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183 Linköping, Sweden
3. Leibniz-Institut für Kristallzüchtung, 12489 Berlin, Germany
4. Department of Electrical and Computer Engineering and Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA
5. Leibniz Institut für Polymerforschung e.V., 01069 Dresden, Germany