1. Department of Applied Physics and Materials Research Center The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong
2. Shenzhen Research Institute The Hong Kong Polytechnic University Shenzhen Guangdong 518057 P. R. China
3. School of Information Science and Engineering Shandong University Qingdao 266237 China
4. Department of Materials Science and Engineering City University of Hong Kong Kowloon Hong Kong