1. Research and Development Center for Advanced Technologies in Microelectronics, National Research Tomsk State University, 36 Lenin Avenue, Tomsk 634050, Russia
2. Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, Nizhny Novgorod 603950, Russia
3. Department of Physics, Center for Materials Science and Nanotechnology, University of Oslo, PO Box 1048, Blindern, NO-0316 Oslo, Norway