1. Crystal Growth Lab, Materials Department 6 (i-meet); FAU Erlangen-Nürnberg; Martensstr. 7 D-91058 Erlangen Germany
2. Laboratori Nazionali del Sud; via S. Sofia 62 95123 Catania Italy
3. IMM-CNR; VIII Strada 5 95121 Catania Italy
4. E.T.C. Epitaxial Technology Center; 16a strada − Pantano d'Arci 95121 Catania Italy