RECTIFICATION IN FULLERENE (C-60) PHTHALOCYANINE THIN-FILM SANDWICH STRUCTURES

Bilayer sandwich structures were fabricated by the sequential thermal evaporation of gold, copper phthalocyanine (CuPc), C-60 and gold onto sapphire substrates. When the current-voltage characteristics of a fre shly made device are measured in an atmosphere of argon, fairly strong rectification is observed. When the bilayer device is exposed to ammo nia vapor, the rectification slowly decreases and almost disappears. I f the device is then placed under vacuum and the ammonia removed, the initial conditions slowly return. We attribute the rectification to th e formation of a p-n junction.