Oxygen induced hysteretic current-voltage characteristics of iron-phthalocyanine thin films.

Electrical transport has been investigated in amorphous and polycrystalline (α-phase) iron phthalocyanine (FePc) thin films grown by molecular beam epitaxy. Measurements carried out in the temperature range of 150–300 K showed hysteric current-voltage (I-V) characteristics at temperatures above 200 K. The I-V characteristics measured during the increasing voltage scan showed a transition from the Ohmic conduction to the trap controlled space charge limited conduction followed by a trap free conduction. During the decreasing voltage scan, trap free conduction was observed in full voltage range. The I-V hysteresis is attributed to the filling of deep surface traps created by chemisorbed oxygen. Amorphous films showed higher hysteresis as well as chemisorbed oxygen content. [ABSTRACT FROM AUTHOR]