1. College of Physics; Jilin University; 2699 Qianjin St. 130012 Changchun P. R. China
2. Taras Shevchenko National University; 64/13 Volodymyrska Str. 01601 Kyiv Ukraine
3. Lashkaryov Institute of Semiconductor Physics; NAS of (UK)raine, 41 Pr. Nauki 03028 Kyiv Ukraine