1. Department of Electrical and Computer Engineering, North Carolina A&T State University, Greensboro, North Carolina 27411, USA
2. Nanoengineering, Joint School of Nanoscience and Nanoengineering, NCA&T State University, Greensboro, North Carolina 27401, USA
3. Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA