1. Shenzhen Engineering Laboratory of Phosphorene and OptoelectronicsKey Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Optoelectronic EngineeringShenzhen University Shenzhen 518060 P. R. China
2. Department of Electronic EngineeringXiamen University Xiamen 361005 P. R. China
3. Institute of Nanosurface Science and EngineeringGuangdong Provincial Key Laboratory of Micro/Nano Optomechatronics EngineeringShenzhen University Shenzhen 518060 P. R. China
4. Faculty of Information TechnologyMacau University of Science and Technology Macao 999078 P. R. China