1. Department of Electrical and Computer Engineering, University of Alberta, 9211-116 St, Edmonton, Alberta T6G 1H9, Canada
2. Nanotechnology Research Centre, National Research Council Canada, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada
3. Department of Materials Science and Engineering, Indian Institute of Technology, Hauz Khas, New Delhi 11016, India
4. Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-4200, United States
5. Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada