1. Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, 22 Hankou Road, Nanjing, Jiangsu 210093, People’s Republic of China
2. Wuxi Little Swan Electric Company, Limited, 18 Changjiang South Road, Wuxi, Jiangsu 214028, People’s Republic of China
3. Jiangsu Key Laboratory for Nano Technology, Nanjing University, 22 Hankou Road, Nanjing, Jiangsu 210093, People’s Republic of China