[1] Research Center for Nanodevices and Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashi-Hiroshima 739-8527, Japan
[2] EBARA Co., Ltd., 4-2-1, Honfujisawa, Fujisawa 251-8502, Japan
[3] Advanced Semiconductor Research Center, National Institute of Advanced Industrial Science and Technology, Japan