1. School of Physics and Optoelectric Engineering, Guangdong University of Technology, Guangzhou Higher Education Mega Center, Guangzhou, 510006, China
2. Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices, Huizhou University, Huizhou 516001, Guangdong, China
3. Experimental Teaching Center, Guangdong University of Technology, Guangzhou, 510006, China
4. Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China