1. Łódź University of Technology, Department of Semiconductor and Optoelectronics Devices, Wólczańska 211/215, 90-924 Łódź, Poland
2. Institute of Physics, Czestochowa University of Technology, al. Armii Krajowej 19, 42-200 Czestochowa, Poland
3. Faculty of Electrical Engineering, Częstochowa University of Technology, al. Armii Krajowej 17, 42-200 Częstochowa, Poland