1. School of Physics, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
2. State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
3. Division of Physical Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand