[1] Univ Catania, Dept Chem Sci, Viale Andrea Doria 6, I-95125 Catania, Italy
[2] STMicroelectronics, Stradale Primosole 50, I-95121 Catania, Italy
[3] CNR IMM, Str 8,5, I-95121 Catania, Italy
[4] INSTM UdR Catania, Viale Andrea Doria 6, I-95125 Catania, Italy