1. Department of Physics, University at Buffalo, Buffalo, New York 14260-1500, United States
2. Department of Electrical Engineering, University at Buffalo, Buffalo, New York 14260-1900, United States
3. School of Electrical, Computer, and Energy
Engineering, and Center for Solid State Electronics Research, Arizona State University, Tempe, Arizona 85287-5706, United States
4. Graduate
School of Advanced Integration Science, Chiba University, 1-33
Yayoi-cho, Inage-ku, Chiba 263-8522, Japan