1. Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China
2. Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
3. Extreme Energy-Density Research Institute, Nagaoka University of Technology, Niigata, Nagaoka 940-2188, Japan