1. Center for III-Nitride Technology, C3NiT-Janzén and Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83 Linköping, Sweden
2. Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83 Linköping, Sweden
3. Terahertz Materials Analysis Center, THeMAC, Linköping University, 581 83 Linköping, Sweden
4. SweGaN AB, Olaus Magnus väg 48A, 583 30 Linköping, Sweden
5. Solid State Physics and NanoLund, Lund University, S-221 00 Lund, Sweden