1. Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2. Department of Applied Science, Republic of China Naval Academy, Kaohsiung, Taiwan
3. Department of Physics and the Center of Crystal Research, National Sun Yat-sen University, Kaohsiung, Taiwan
4. Department of Materials and Optoelectronic Science, National Sun Yat-sen University, Kaohsiung, Taiwan
5. Institute of Electronics Engineering, National Tsing Hua University, Hsinchu, Taiwan
6. Department of Electronics Engineering, National Chiao Tung University, Hsinchu, Taiwan