1. Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
2. Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
3. Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw, Poland
4. Institute of Optoelectronics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland