1. Department of Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus, Ohio 43210, USA
2. Columbus School for Girls, 56 S. Columbia Ave., Columbus, Ohio 43209, USA
3. Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140, New Zealand
4. The MacDiarmid Institute for Advanced Materials and Nanotechnology, Laby 410 Kelburn Parade, Wellington, New Zealand
5. Semiconductor Research Center, Wright State University, 3640 Colonel Glenn Hwy., Dayton, Ohio 45435, USA
6. Department of Electrical and Computer Engineering, The Ohio State University, 205 Dreese Lab, 2015 Neil Ave., Columbus, Ohio 43210, USA