Photo-Induced Polarization Recovery in PZT Thin Film Capacitors

Abstract

ABSTRACTLead Zirconate Titanate (PZT) ferroelectric thin film capacitors were fabricated with metallic platinum and conducting Indium Tin Oxide (ITO) contacts. PZT thin films were fabricated using metallorganic decomposition (MOD) while a combination of MOD and RF-sputtering was used in fabricating the ITO-PZT-ITO capacitors. Photo-induced changes, manifested by an increase in switchable polarization, were studied before and after 108 switching cycles fatigue using white and monochromatic light. An increase in photo-induced changes was observed at 3.65eV light energies using monochromatic light using both capacitors. The increase was attributed to the excitation of electrons from PZT valence band into the conduction band causing an increase in film conductivity. However, polarization increase in Pt-PZT-Pt capacitor was more pronounced than ITO-PZT-ITO when white light was used. Some of the response in fatigued Pt-PZT-Pt capacitors was attributed to the excitation of electrons from the platinum Fermi level to oxygen vacancy sites trapped at the Pt-PZT interface by absorption of infrared radiation of white light. The latter observation implied a relationship between PZT fatigue and photo-induced effects.