Fatigue effect in ferroelectric PbZr1−xTixO3 thin films

Abstract

Pb Zr 1 − x Ti x O 3 (PZT) is one preferred ferroelectric material being used in nonvolatile ferroelectric random access memory devices. The use of oxide electrodes like IrO2 or SrRuO3 (SRO) is necessary to suppress the serious loss of polarization due to bipolar voltage cycling. Although, there are a number of models under discussion, the origin of the fatigue phenomenon is still not completely understood. In this paper, the fatigue effect of ferroelectric Pb(Zr0.40,Ti0.60)O3 thin films has been studied in detail. To achieve a deeper understanding of the effect, several PZT samples with different electrode materials were investigated. After determining the dependence of the single fatigue parameters, a simulation approach was made to analyze the fatigue effect qualitatively. A sample with SRO electrodes was measured up to 1013cycles and no fatigue of the switchable polarization was observed.

Bipolar and unipolar electrical fatigue in ferroelectric lead zirconate titanate thin films: An experimental comparison study

“…One can see that the fatigue characteristics of our PZT film show a logarithmic dependence on cycle number and polarization fatigue becomes more severe and eventually saturated for the capacitors driven by higher cycling voltages, consistent with the general features reported in the literature. 2,[15][16][17][18][19] The electric field/voltage dependence of fatigue data in Fig. 2 can be well explained by the LPD-SICI model ͑LPD-SICI stands for local phase decomposition initiated by switching-induced charge injection͒: 2,20 the higher fatigue rates at higher applied voltages are caused by higher P r ͑E appl ͒ and consequently more intensive charge injection and phase decomposition at the domain nucleation sites ͑in-cluding the nucleation sites on switched domain walls͒ at the electrode-film interface.…”

Barrier height at(Ba,Sr)TiO3/Ptinterfaces studied by photoemission

“…The metallic contact has, therefore, a strong impact on the leakage current behavior. 5,6 In addition, dielectric properties, 7 cycling stability, 8 and high frequency dielectric losses 9 are influenced by contact properties. The properties of the BST/Pt contact have already been extensively investigated by different techniques.…”

Reduction-induced Fermi level pinning at the interfaces between Pb(Zr,Ti)O3 and Pt, Cu and Ag metal electrodes

“…in dynamic random access memory (DRAM), piezoelectric sensors and actuators [1,2,3,4]. For PZT thin film, the cycling stability, imprint performance and leakage current strongly depend on the used electrode material [5,6,7,8]. Electrical fatigue causes a reduction of polarization with increasing switching numbers and is a severe limitation of device operation.…”