1. National University of Science and Technology MISiS, Moscow 194017, Russia
2. Ioffe Physico-Technical Institute, 26 Polytekhnicheskaya Str., St. Petersburg 194021, Russia
3. Submicron Heterostructures for Microelectronics Research and Engineering Center, St. Petersburg 194021, Russia
4. Department of Materials Science and Engineering, Korea University, Seoul 02841, South Korea
5. Technological Institute for Superhard and Novel Carbon Materials, 7 Centralnaya St., Troitsk, Moscow 142190, Russia
6. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, USA