1. Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
2. Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Šlechtitelů 27, 78371 Olomouc, Czech Republic
3. School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, P. R. China
4. Institute of Surface Micro and Nano Materials, Xuchang University, Xuchang, Henan 461002, P. R. China
5. Nanotechnology Centre, VŠB–Technical University of Ostrava, 17. listopadu 2172/15, 708 00 Ostrava-Poruba, Czech Republic