MINIMIZATION OF FATIGUE IN FERROELECTRIC-FILMS

On the basis of a quantitative fatigue model, various methods to minimize fatigue in oxide ferroelectric films are discussed. The model attributes fatigue to domain pinning by space charge that is caused by oxygen vacancy entrapment at the interfaces (e.g., electrode-ferroelectric, domain boundaries, etc.). Based on this model, it is demonstrated that fatigue can be minimized by a) using conductive oxide electrodes (e.g., RuO2) that prevent space charge formation at the interfaces, b) by addition of donor dopants (e.g., Nb, La in Pb(ZrxTi1-x)O-3) that reduce the oxygen vacancy concentration, and c) by utilizing ferroelectric materials (e.g., SrBi2(TaxNb1-x)(2)O-9) that have a low intrinsic defect concentration.