1. Physics
Division, Institute of Mathematical Sciences and Physics, University of the Philippines Los Baños, College, Los Baños, 4031, Laguna, Philippines
2. Department
of Physics, National Taiwan University, Taipei, Taiwan, 10617
3. Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan, 11529
4. Department
of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, Taiwan, 80424