1. Center for Nanocharacterization, Korea Research Institute of Standards and Science, 209 Gajeong-Ro, Yuseong-Gu, Daejeon 305-340, Republic of Korea, Insilicotech Company Limited, A-1101 Kolontripolis, 210, Geumgok-Dong, Bundang-Gu, Seongnam, Gyeonggi-Do 463-943, Republic of Korea, and Materials and Process Simulation Center (MC 139-74), California Institute of Technology, Pasadena, California 91125