1. National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Department of Micro/Nano Electronics, School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
2. Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
3. Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
4. Chemical Science and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
5. Department of Materials Science and Engineering, Rutgers University, Piscataway, New Jersey 08854, USA