1. National Institute for Research and Development in Microtechnologies (IMT), Strada Erou Iancu Nicolae 126A, 077190 Voluntari, Romania
2. Physics Faculty, University of Bucharest, P.O. Box MG-11, 077125 Bucharest, Romania
3. Academy of Romanian Scientists, Strada Ilfov, Nr. 3, 050044 Bucharest, Romania