Experimental Evidences of the Space Charge Activity in Pb(Ti,Zr)O₃ and (Ba,Sr)TiO₃ Ferroelectric Thin Film Structures

Abstract

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.

Keywords:

• PZT and BST ferroelectric thin films
• space charge layers
• oxygen vacancy

PACS:

• 77.22.−d
• 77.55.+f
• 77.80.−e
• 77.84.−s

Acknowledgment

The author express his gratitude to V.V. Lemanov for helpful discussions.