1. Energy Technology Research Institute (ETRI); National Institute of Advanced Industrial Science and Technology (AIST); 1-1-1 Umezono Tsukuba Ibaraki 305-8568 Japan
2. Advanced Low Carbon Technology Research and Development Program (ALCA); Japan Science and Technology Agency (JST); c/o AIST Japan
3. Core Research for Evolutional Science and Technology (CREST); Japan Science and Technology Agency (JST); c/o AIST Japan
4. Wide Bandgap Materials Group; National Institute of Materials Science (NIMS); Tsukuba Ibaraki 305-0044 Japan