1. National Institute of Materials Physics, 405A Atomistilor Str., P.O. Box MG-7, 077125 Magurele, Ilfov, Romania
2. University Politehnica of Bucharest, Faculty of Electronics,
Telecommunications and Information Technology, Bdul Iuliu Maniu 1-3, sector 6, Bucharest 061071, Romania
3. University of California, 3123 Bainer
Hall, Davis, California 95616, United States