1. Materials Science and Engineering Department, University of California, San Diego, California 9500, USA
2. Materials Science and Engineering Department, Stanford University, Stanford, California 94305, USA
3. Materials Department, University of California, Santa Barbara, California 93106, USA
4. Global Foundries, 2600 Great America Way, Santa Clara, California 95054, USA
5. Department of Physics, Texas State University, San Marcos, Texas 78666, USA