RUAMMAITREE, Akkawat, Department of Physics, Faculty of Science and Technology, Thammasat University, Phahon Yothin, Khlong Luang, Pathum Thani 12120, Thailand; Thammasat University Research Unit in Synthesis and Applications of Graphene, Thammasat University, Phahon Yothin, Khlong Luang, Pathum Thani 12120, Thailand, Thailand