[1] Univ Barcelona, Dept Appl Phys, C-Marti i Franques,1, Barcelona 08028, Spain
[2] Univ Barcelona, Inst Nanosci & Nanotechnol IN2UB, ENPHOCAMAT Grp, C-Marti i Franques,1, Barcelona 08028, Spain
[3] Univ Barcelona, Dept Inorgan & Organ Chem, C-Marti i Franques,1, Barcelona 08028, Spain
[4] Univ Ind Santander, Escuela Fis, Carrera 27 Calle 9 Ciudad Univ, Bucaramanga, Colombia