1. Faculty of Electronics, Hanoi University of Industry, 298 Cau Dien, Hanoi, Vietnam
2. Faculty of Electronics and Telecommunications, VNU University of Engineering and Technology, E3 Building, 144 Xuan Thuy, Hanoi, Vietnam
3. Department of Physico - Chemistry of Non-metallic Materials, Institute for Tropical Technology, Vietnam Academy of Science and Technology (ITT, VAST), 18 Hoang Quoc Viet - Cau Giay, Hanoi, Vietnam