1. Photovoltaics and Optoelectronic
Devices Group, Departament de Física, Universitat Jaume I, 12071 Castelló, Spain
2. National Institute of Lasers, Plasma and Radiation Physics, Atomistilor
409 Street, P.O. Box MG 36 Bucharest-Magurele, 077125 Romania
3. Faculty of Physics, University of Bucharest, Atomistilor 405 Street, MG-11
Bucharest-Magurele, 077125 Romania