1. State Key Laboratory of Electronic Thin Films and Integrated DevicesUniversity of Electronic Science and Technology of China Chengdu 610054 P. R. China
2. Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of Technology Beijing 100081 P. R. China
3. Institute of Microelectronics of Chinese Academy of Sciences Beijing 100029 P. R. China
4. University of Chinese Academy of Sciences Beijing 100049 P. R. China
5. State Key Laboratory of Material Processing and Die and Mould TechnologySchool of Materials Science and EngineeringHuazhong University of Science and Technology Wuhan 430074 P. R. China
6. Technology Development CenterMetatest Optoelectronic CO. LTD Nanjing 210008 P. R. China
7. Academy for Advanced Interdisciplinary Studies and Department of PhysicsSouthern University of Science and Technology Shenzhen 518055 China