Institution: | (1) Department of Solid-State Electronics, Uzhgorod State University, Uzhgorod, 294000, Ukraine (Fax: +38-031/223-2339, E-mail: kiki@sse.univ.uzhgorod.ua), UA;(2) Department of Solid State Physics, L. Kossuth University, H-4010 Debrecen, P.O. Box 2, Hungary, HU |