1. Department of Physics; Faculty of Science; King Mongkut's Institute of Technology Ladkrabang; Chalongkrung Rd. Ladgrabang Bangkok 10520 Thailand
2. Thermoelectric and Nanotechnology Research Center; Faculty of Science and Technology; Rajamangala University of Technology Suvarnabhumi; 60 Moo 3, Asian Highway Huntra Phranakhon Si Ayutthaya 13000 Thailand
3. Integrated Nanotechnology Research Center; Department of Physics; Faculty of Science; Khon Kaen University; Khon Kaen 40002 Thailand