1. College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, China
2. Institute of Physics, Jan Długosz University in Częstochowa, Ave. Armii Krajowej 13/15, Częstochowa 42-200, Poland
3. School of Electronic and Electrical Engineering, Nanyang Institute of Technology, Nanyang 473004, China
4. College of Material Science and Engineering, Guilin University of Technology, Guilin 541004, China