1. Deparment of Chemistry and Biochemistry and California NanoSystems Institute, University of California at Los Angeles, Los Angeles, California 90095, United States
2. International Center for Materials Nanoarchitectonics (MANA), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
3. Department of Electrical Engineering, University of California at Los Angeles, Los Angeles, California 90095, United States
4. Micro/Nano Technology Department, Space Materials Laboratory, The Aerospace Corporation, Los Angeles, California 90009, United States
5. Department of Materials Science and Engineering, University of California at Los Angeles, Los Angeles, California 90095, United States