1. Department of Materials Science Fudan UniversityShanghai 200433P. R. China
2. Materials Sciences Division Lawrence Berkeley National LaboratoryBerkeleyCA94720USA
3. Advanced Light Source Lawrence Berkeley National LaboratoryBerkeleyCA94720USA
4. Electrical Engineering and Computer Sciences University of CaliforniaBerkeleyCA94720USA
5. Materials Science and Engineering University of California at BerkeleyBerkeleyCA94720USA