EFFECTS OF OPTICAL ILLUMINATION ON FATIGUED LEAD-ZIRCONATE-TITANATE CAPACITORS

PZT thin films with the composition PbZr0.53Ti0.47O3 were deposited via metallo-organic decomposition (MOD) and rapid thermally processed (RTP) at 725 degrees C and 875 degrees C. A technique using ''white'' light to photostimulate electrons into unassociated oxygen vacancies was employed to study fatigue mechanisms. We propose that free electrons stimulated by light illumination fill doubly charged oxygen vacancies and restore local charge equilibrium within the material near the PZT/Pt interfaces. The restoration of charge was explained based on changes in the energy band diagram of the PZT/Pt interface due to oxygen vacancy build up. It was found that this restoration of charge resulted in nearly a 50% recovery of lost polarization. Therefore, we conclude that oxygen vacancy migration and subsequent build up at the PZT/Pt interfaces is a likely source of fatigue.