Lihui Liu1, Xin Liu2, Zhaoyao Zhan1, Weiling Guo2, Chen Xu2, Jun Deng2, Dinko Chakarov3, Per Hyldgaard1, Elsebeth Schröder1, August Yurgens1 and Jie Sun1,2,*
1 Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden
2 College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing, China
3 Department of Applied Physics, Chalmers University of Technology, Göteborg, Sweden
