1. Northwestern University Department of Materials Science and Engineering, , Evanston, Illinois, United States
2. Kobe University Department of Electrical and Electronic Engineering, Graduate School of Engineering, , Rokkodai, Nada, Kobe, Japan
3. Northwestern University Department of Electrical and Computer Engineering, , Evanston, Illinois, United States
4. Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University , Evanston, Illinois, United States
5. Northwestern University International Institute for Nanotechnology (IIN), , Evanston, Illinois, United States