1. Stepanov Institute of Physics, National Acad. Sci. of Belarus, F. Skaryna Ave. 68, 220072 Minsk, Belarus
2. Institute of Materials Science and Applied Research, Vilnius University, Sauletekio ave. 9‐3, 10222 Vilnius, Lithuania
3. SOITEC S.A., Parc Technologique des Fontaines, 38190 Bernin, France
4. AIXTRON AG, Kackertstr. 15‐17, 52072 Aachen, Germany
5. Institut für Theoretische Elektrotechnik, RWTH Aachen, Kopernikusstr. 16, 52074 Aachen, Germany