[1] STAR, Inst Microelect, Singapore 117685, Singapore
[2] SEMATECH, Austin, TX 78741 USA
[3] Natl Univ Singapore, Dept Elect & Comp Engn, Silicon Nano Device Lab, Singapore 119260, Singapore
[4] Natl Univ Singapore, Dept Elect & Comp Engn, Silicon Nano Device Lab, Singapore 119260, Singapore
[5] Korea Adv Inst Sci & Technol, Dept Elect Engn, Taejon 305701, South Korea