1. Department of Electrical and Electronics Engineering, Kangwon National University, 1 Gangwondaehakgil, Chuncheon-si, Gangwon-do 24341, South Korea
2. Department of Materials Science and Engineering, The University of Texas at Dallas, 800 West Campbell Road, Richardson, Texas 75080, USA
3. Texas Instruments, 13121 TI Blvd, Dallas, Texas 75243, USA