1. Kotel’nikov Institute of Radio Engineering and Electronics of Russian Academy of Science, Mokhovaya str. 11, bld.7, Moscow 125009, Russia
2. Saratov State University, Astrakhanskaya str. 83, bld.5, Saratov 410012, Russia
3. University Laboratory “Nanoscience and Nanotechnology”, University of Architecture, Civil Engineering and Geodesy, blvd. Hr. Smirnenski 1, Sofia 1164, Bulgaria