Experimental Evidences of the Space Charge Activity in Pb(Ti,Zr)O3and (Ba,Sr)TiO3Ferroelectric Thin Film Structures

Highly inhomogeneous electronic structure of Pb(Ti,Zr)O3 sol-gel thin ferroelectric films with metal electrodes including a n-type semiconducting near-electrode layer and a p-n junction in the film's interior is revealed by means of a dielectric spectroscopy and photoelectric study. Charged oxygen vacancies accumulation near the electrodes is believed as a reason for a decrease of coercive field with decreasing a speed of a bias voltage variation during measurement of C-V dependences in Ni/PZT/Pt thin film structures. Slow capacitance relaxation and transient charging/discharging currents in laser ablated (Ba,Sr)TiO3 thin films with conducting oxide electrodes after a step voltage switching on and off are explained by the p-n junction formation due to the oxygen vacancy redistribution and near-electrode Schottky barriers charging/discharging processes.