1. Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia
2. Rzhanov Institute of Semiconductor Physics, Siberian Division, Russian Academy of Sciences, Pr. Lavrentieva 13, 630090 Novosibirsk, Russia
3. National Research Centre “Kurchatov Institute,” Pl. Akademika Kurchatova 1, 123182 Moscow, Russia
4. Novosibirsk State University, Pirogova Str. 2, 630090 Novosibirsk, Russia