1. Department of Semiconductor and Display Engineering Sungkyunkwan University Suwon 440‐746 South Korea
2. Memory Technology Design Team Samsung Electronics Co. Hwasung 18448 South Korea
3. Department of Electrical and Computer Engineering Sungkyunkwan University Suwon 440‐746 South Korea
4. SKKU Advanced Institute of Nano Technology (SAINT) Sungkyunkwan University Suwon 440‐746 South Korea
5. Jet Propulsion Laboratory (JPL) California Institute of Technology Pasadena CA 91109 USA
6. Research Laboratory of Electronics Massachusetts Institute of Technology (MIT) Cambridge MA 02139‐4307 USA
7. School of Advanced Materials Science and Engineering Sungkyunkwan University Suwon 440‐746 South Korea
8. Department of Chemical and Biomolecular Engineering Yonsei University Seoul 120‐749 South Korea