1. National Sun Yat-Sen University,Pei-Yu Wu and Tsung-Ming Tsai are with the Department of Materials and Optoelectronic Science,Kaohsiung,Taiwan,80424
2. National Yang Ming Chiao Tung University,Xin-Ying Tsai and Simon M. Sze are with the Department of Electronics Engineering,Hsinchu,Taiwan.,30010
3. National Sun Yat-Sen University,Ting-Chang Chang is with Department of Physics, and also with College of Semiconductor and Advanced Technology Research,Kaohsiung,Taiwan,804