1. Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
2. Department of Physics, National Taiwan University, Taipei, 10617, Taiwan
3. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
4. Institute of Microelectronics & Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan
5. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
6. Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, 80424, Taiwan