1. Hubei Key Laboratory of Micro/Nano-Electronic Materials and Devices, School of Microelectronics, Hubei University, Wuhan 430062, P. R. China
2. Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong NSW2500, Australia
3. School of Physics and Materials Science, Jiangxi Key Laboratory for Two-Dimensional Materials and Jiangxi Engineering Laboratory for Advanced Functional Thin Films, Nanchang University, Nanchang 330031, P. R. China
4. Department of Materials Science and Engineering, National University of Singapore, Singapore 117574, Singapore
5. National University of Singapore (Chongqing) Research Institute, Chongqing Liang Jiang New Area, Chongqing 401120, P. R. China