1. School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
2. Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
3. Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand
4. Institute of Nanomaterials Research and Innovation for Energy (IN-RIE), Khon Kaen University, Khon Kaen 40002, Thailand