1. Key
Laboratory of Polar Materials and Devices, Ministry of Education,
and Department of Electronic Engineering, East China Normal University, 500 Dongchuan Road, Minhang District, Shanghai 200241, China
2. Shanghai
Key Laboratory of Multidimensional Information Processing, East China Normal University, Shanghai 200241, China
3. Department
of Physics and Materials Science, City University of Hong Kong, Tat Chee
Avenue, Kowloon, Hong Kong, China