1. Department of Physics, Taras Shevchenko National University of Kyiv, Volodymyrska str., 64/13, Kyiv 01601, Ukraine
2. Department of Radiophysics, Electronics, and Computer Systems, Taras Shevchenko National University of Kyiv, Volodymyrska str., 64/13, Kyiv 01601, Ukraine
3. I. Frantsevich Institute for Problems in Materials Science National Academy of Sciences of Ukraine, Krzhyzhanosky str, 3, Kyiv 03142, Ukraine