Degradation of ferroelectric thin films: A defect chemistry approach

Abstract

Degradation of the switchable polarization in ferroelectric thin films of metal oxides is attributed to the migration of oxygen vacancies. Cyclic voltage pulses applied to thinned ceramic samples of BaTiO₃ show that samples in which the oxygen vacancy concentration has been increased by the addition of acceptor dopants degrade more rapidly than updoped samples, while samples in which the oxygen vacancy concentration has been suppressed by the addition of donor dopants exhibit increased stability. Similar, but smaller trends are demonstrated in PZT thin films. It is shown that for donor-doping of PZT to be effective, the loss of PbO must be carefully controlled.

Keywords:

• Ferroelectric fatigue
• PbO-loss
• oxygen vacancies
• donor-doping