1. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
2. Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan
3. School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore
4. Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87123, USA
5. Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan
6. Graduate School of Advanced Technology, National Taiwan University, Taipei 10617, Taiwan
7. Taiwan Semiconductor Research Institute, Hsinchu 300091, Taiwan