[1] Khon Kaen Univ, Mat Sci & Nanotechnol Program, Fac Sci, Khon Kaen 40002, Thailand
[2] Khon Kaen Univ, Dept Phys, Fac Sci, Khon Kaen 40002, Thailand
[3] Khon Kaen Univ, INRC, Khon Kaen 40002, Thailand
[4] Natl Met & Mat Technol Ctr MTEC, Pathum Thani 12120, Thailand
[5] Suranaree Univ, Inst Sci, Sch Phys, Nakhon Ratchasima 30000, Thailand