1. Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2. Department of Photonics, National Sun Yat-sen University, Kaohsiung, Taiwan
3. Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
4. Department of Materials and Optoelectronic Science, Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
5. Department of Computer Science, Boston University, Boston, MA, USA
6. College of Semiconductor and Advanced Technology Research, National Sun Yat-sen University, Kaohsiung, Taiwan
7. Department of Physics and the Center of Crystal Research, National Sun Yat-sen University, Kaohsiung, Taiwan
8. Department of Electronics Engineering and the Institute of Electronics, National Chiao-Tung University, Hsinchu, Taiwan