1. Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
2. Sandia National Laboratories, Livermore, California 94550, United States
3. Department of Materials Science and Engineering, National Yang Ming Chiao Tung University, Hsinchu 300, Taiwan
4. Sandia National Laboratories, Albuquerque, New Mexico 87185, United States