1. Center for Integrated Nanostructure Physics; Institute for Basic Science (IBS); Sungkyunkwan University; Suwon 16419 Republic of Korea
2. Department of Energy Science; Sungkyunkwan University; Suwon 16419 Republic of Korea
3. Department of Physics; Sungkyunkwan University; Suwon 16419 Republic of Korea
4. Department of Cogno-mechatronics Engineering; Pusan National University; Busan 46241 Republic of Korea
5. Department of Chemistry and Centre for Advanced 2D Materials (CA2DM); National University of Singapore; 3 Science Drive 3 Singapore 117543
6. UNIST Central Research Facilities; Ulsan National Institute of Science and Technology (UNIST); Ulsan 689-798 Republic of Korea