1. Compound Semiconductor Technology, RWTH Aachen University, Sommerfeldstraße 18, 52074 Aachen, Germany
2. Peter-Grünberg-Institute (PGI 7/10) and JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
3. Faculty of Georesources and Materials Engineering, RWTH Aachen University, Intzestr. 1, 52072 Aachen, Germany
4. AIXTRON SE, Dornkaulstr. 2, 52134 Herzogenrath, Germany