Correlations Among Degradations in Lead Zirconate Titanate thin Film Capacitors

Abstract

Many attempts have been made to reduce degradation properties of Lead Zirconate Titanate (PZT) thin film capacitors. Although each degradation property has been studied extensively for the sake of material improvement, it is desired that they be understood in a unified manner in order to reduce degradation properties simultaneously. This can be achieved if a common source(s) of degradations is identified and controlled. In the past it was noticed that oxygen vacancies play a key role in fatigue, leakage current, and electrical degradation/breakdown of PZT films.It is now known that space charges (oxygen vacancies, mainly) affect ageing, too. Therefore, a quantitative ageing mechanism is proposed based on oxygen vacancy migration under internal field generated by either remanent polarization or spontaneous polarization.Fatigue, leakage current, electrical degradation, and polarization reversal mechanisms are correlated with the ageing mechanism in order to establish guidelines for simultaneous degradation control of PZT thin film capacitors. In addition, the current pitfalls in the ferroelectric test circuit is discussed, which may cause false retention, imprint, and ageing.

Enhanced Temperature Stability of (1 − x)(K0.5Na0.5)0.94Li0.06NbO3-x(Bi0.5Na0.5)TiO3 Lead-Free Piezoelectric Ceramics

“…21,23 Those results indicated that BNT doping had induced the pinning effect of domain walls due to the existence of oxygen vacancies, 24,25 leading to the enhanced Q m factor. 26 On the other hand, the ionic radius of Bi 3+ is 1.03 Å , so it may have substituted the A-site ions K + (1.38 Å ) and Na + (1.02 Å ), 27 which also caused the shrinkage of the KNLN6 unit cell and thus induced the pinning effect of domain walls.…”

Ferroelectric fatigue of Pb(Zr,Ti)O3 thin films measured in atmospheres of varying oxygen concentration

“…3,4 While evidence in support of either model exists, a considerable number of observations seem to suggest that the scenario involving oxygen vacancies is more likely. [5][6][7][8][9] To test this hypothesis, fatigue tests were performed on Pb͑Zr,Ti͒O 3 ͑PZT͒ thin films in atmospheres of varying oxygen partial pressure.…”

Metalorganic chemical vapor deposition of ferroelectric SrBi2Ta2O9 thin films

“…Several models can be found in the literature to explain the individual degradation mechanisms. Recently, Desu and Yoo 3 have proposed a unified model in which oxygen vacancies are cited as the common source for most degradation phenomena. The model suggests two possible solutions to overcome fatigue: reducing entrapments by changing the nature of the electrode/ferroelectric interface and controlling defect density of the ferroelectrics.…”