1. Graphene Research Team ICT Creative Research Lab. Electronics and Telecommunications Research Institute (ETRI) Daejeon 34129 Republic of Korea
2. Department of Materials Science and Engineering University of Texas at Dallas Richardson TX 75080 USA
3. School of ETRI (ICT‐Advanced Device Technology) University of Science and Technology (UST) Daejeon 34113 Republic of Korea
4. Department of Physics Education Chonnam National University Gwangju 61186 Republic of Korea
5. ICT Creative Research Lab. Electronics and Telecommunications Research Institute (ETRI) Daejeon 34129 Republic of Korea