1. Department of Physics, Tamkang University, New Taipei City 251301, Taiwan
2. Department of Electronics, Smt. Kasturbai Walchand College, Sangli 416416, Maharashtra, India
3. Bachelors’s Program in Advanced Materials Science, Tamkang University, New Taipei City 251301, Taiwan
4. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
5. Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan
6. Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
7. Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan
8. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
9. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
10. Department of Physics, National Taiwan University, Taipei 10617, Taiwan