1. Department of Physics, Tomsk State University of Control Systems and Radioelectronics, 40 Lenin Avenue, Tomsk 634050, Russian Federation
2. Institute of High Current Electronics SB RAS, 2/3 Akademichesky Ave., Tomsk 634055, Russian Federation
3. Department of Electron Technics and Technology, Belarusian State University of Informatics and Radioelectronics, 6 P. Brovki Str., Minsk 220013, Belarus