1. Department of Electrical Engineering and Computer Science, Daegu Gyeongbuk Institute of Science & Technology (DGIST) 1 , Daegu 42988, South Korea
2. Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science & Technology (DGIST) 2 , Daegu 42988, South Korea
3. Convergence Technology Division, Korea Advanced Nano Fab (KANC) 3 , Suwon 16229, South Korea