1. Institute of Applied Research, Vilnius University, Saulėtekio 10, 10223 Vilnius, Lithuania
2. Translucent Inc., 952 Commercial St., Palo Alto, California 94303, USA
3. The Cambridge Centre for Gallium Nitride, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
4. Center for Physical Sciences and Technology, Savanoriu av. 231, 02300 Vilnius, Lithuania