1. Department of Physics and Zhejiang Engineering Research Center of MEMS, Shaoxing University, Shaoxing 312000, P. R. China
2. Science and Technology on Microsystem Laboratory, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, P. R. China
3. Shangyu Coll, Shaoxing University, Shaoxing 312300, P. R. China