1. Department of Chemical Engineering, New Mexico State University, Las Cruces, New Mexico 88003, United States
2. Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
3. Department of Electrical and Computer Engineering, Texas A&M University, College Station, Texas 77843, United States
4. Jiangsu Key Laboratory of Thin Films, School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China