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Page 6 of 10 Li et al. Microstructures 2023;3:2023007 https://dx.doi.org/10.20517/microstructures.2022.27

Figure 4. Frequency-dependent (A) dielectric constant and (B) dielectric loss for PZO-based films at room temperature. PZO: PbZrO .
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Figure 5. (A) The P-E loops of PZO-based films at 800 kV/cm, and corresponding (C) the polarization difference value of Δ P (P - P ).
max r
(B) The I-E loops of PZO-based films at 800 kV/cm, and corresponding (D) the switching field value of Δ E (E - E ). PZO: PbZrO . 3
F
A
strength enhances compared to pure PZO films, as exhibited in Figure 6B and C. The leakage current is a
crucial parameter for evaluating dielectric film's electric properties and conduction mechanisms [20-23] .
Figure 6D illustrates the leakage current for PZO-based films as a function of the electric field. It can be seen
that the curve of leakage current of pure PZO films can be divided into two parts: For low electric field, the
leakage conductivity belongs to the bulk-limited Ohmic mechanism. The Fowler-Nordheim tunneling (FN)
mechanism dominates at high electric field. A similar phenomenon also exists in PBZ and PZB films. Note
that the transition field from bulk-limited to FN mechanism gradually reduces for pure PZO, PBZ, and PZB
films, which may be related to different defect types in aliovalent doping PZO at A/B sites. Compared to the
lead vacancy, the oxygen vacancy may easily contribute more leakage currier; hence, the transformation
field of PZB from Ohmic into FN mechanism reduces compared to PBZ.