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

Electrical transport has been investigated in amorphous and polycrystalline (alpha-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. (c) 2008 American Institute of Physics. [DOI: 10.1063/1.2990060]