[1] Feng Chia Univ, Grad Inst, Taichung 40724, Taiwan
[2] Feng Chia Univ, Dept Elect Engn, Taichung 40724, Taiwan
[3] Natl Nano Device Labs, Hsinchu, Taiwan
[4] Natl Chiao Tung Univ, Inst Elect, Hsinchu 30039, Taiwan
[5] Natl Chiao Tung Univ, Dept Elect, Hsinchu 30039, Taiwan