1 Center for Integrated Research of Future Electronics (CIRFE), Institute of Materials and Systems for Sustainability (IMaSS), Nagoya University, Aichi, 464-8601, Japan. a_tanaka@nuee.nagoya-u.ac.jp.
2 National Institute for Materials Science, Tsukuba, 987-6543, Japan. a_tanaka@nuee.nagoya-u.ac.jp.
3 Research & Development Department, Electron Tube Division, Hamamatsu Photonics K. K., Shizuoka, 438-0193, Japan.
4 Center for Integrated Research of Future Electronics (CIRFE), Institute of Materials and Systems for Sustainability (IMaSS), Nagoya University, Aichi, 464-8601, Japan.
5 Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Aichi, 466-8555, Japan.