1. Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education International Center for Dielectric Research&Shannxi Engineering Research Center of Advanced Energy Materials and Devices, Xi’an Jiaotong University, 710049 Xi’an, China
2. Frontier Institute of Science and Technology (FIST), Micro- and Nano-technology Research Center of State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, 710049 Xi’an, China
3. Center for Micro and Nano Device, Department of Physics, COMSATS Institute of Information Technology, Islamabad 44500, Pakistan