1. Department of Applied Physics, Uzhhorod National University, Uzhhorod, Ukraine
2. Department of Physics, Kyiv National University of Technologies and Design, Kyiv, Ukraine
3. Institute of Physics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
4. V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
5. Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia