1. Key Laboratory of Micro-nano Electric Sensing Technology and Bionic Devices, Department of Network Security and Information Technology, Yili Normal University, Yining 835000, P. R. China
2. Department of Electronics and Engineering, Yili Normal University, Yining 835000, P. R. China
3. National Key Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093, P. R. China