Affiliation: | a Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea b National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA c National Research Laboratory for Nano Quantum Electronics Devices, Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791, Republic of Korea d Department of Electronic Materials Engineering, Kwangwoon University, Seoul 139-701, Republic of Korea e Thin Film Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea |