Growth and study of antiferroelectric lead zirconate thin films by pulsed laser ablation

Abstract

Antiferroelectric lead zirconate ͑PZ͒ thin films were deposited by pulsed laser ablation on platinum-coated silicon substrates. Films showed a polycrystalline pervoskite structure upon annealing at 650°C for 5-10 min. Dielectric properties were investigated as a function of temperature and frequency. The dielectric constant of PZ films was 220 at 100 kHz with a dissipation factor of 0.03. The electric field induced transformation from the antiferroelectric phase to the ferroelectric phase was observed through the polarization change, using a Sawyer-Tower circuit. The maximum polarization value obtained was 40 C/cm 2 . The average fields to excite the ferroelectric state, and to reverse to the antiferroelectric state were 71 and 140 kV/cm, respectively. The field induced switching was also observed through double maxima in capacitance-voltage characteristics. Leakage current was studied in terms of current versus time and current versus voltage measurements. A leakage current density of 5ϫ10 Ϫ7 A/cm 2 at 3 V, for a film of 0.7 m thickness, was noted at room temperature. The trap mechanism was investigated in detail in lead zirconate thin films based upon a space charge limited conduction mechanism. The films showed a backward switching time of less than 90 ns at room temperature.

Dielectric Relaxation Phenomenon in Ferroelectric Perovskite-related Structures

“…Activation energy values (for dc conductivity contribution, U dc , and the hopping process, U H ) for the studied compositions, obtained from the fitting of the experimental data by using the equations (8) and (9) . Arrhenius' dependence for the dc conductivity (σ dc ) and the hopping frequency (ω H ) (A and B, respectively), below T m, for the studied PSTM-x compositions As can be seen, the activation energy values for the dc conductivity are very close to the activation energy values of the ionic conductivity by oxygen vacancies in perovskite type ferroelectric oxides (Jiménez & Vicente, 1998;Bharadwaja & Krupanidhi, 1999;Chen et al, 2000;Smyth, 2003). Thus, it can be concluded that oxygen vacancies are the most likely charge carriers operating in these ceramics below T m .…”

“…The oxygen vacancies are always related to dielectric relaxation phenomenon, as well as to the electrical conductivity for ferroelectric perovskite-related structures, considering that these are the most common mobiles species in such structures (Jiménez & Vicente, 1998;Bharadwaja & Krupanidhi, 1999;Chen et al, 2000;Islam, 2000;Yoo et al, 2002;Smyth, 2003;Verdier et al, 2005). For ABO 3 -type perovskite structures, the BO 6 octahedra play a critical role in the demonstration of the ferroelectric properties.…”

Influence of diffuse phase transition on the anelastic behavior of Nb-doped Pb(Zr0.53Ti0.47)O3 ceramics

“…From the curve fitting with Equation 5, it was found that the dc conductivity process has an activation energy close to 1.0eV, which is almost invariant with frequency. Values in the range 0.6 -1.2eV have been associated with doubly ionized oxygen vacancies in various perovskite oxides[34][35][36].Nevertheless, donor doping in PZT, such as Nb 5+ , replaces the B-site host cations in ABO 3 structure. Thus, the excess of positive charge may be compensated by lead vacancies formation accompanied by a strong reduction of the oxygen vacancies.…”

Dielectric, ferroelectric and piezoelectric properties of Ca0.1Sr0.9Bi2Nb2O9 ceramic

“…(2). The value of activation energies E a , calculated by linear fitting of the data points, were 1.45, 1.24 and 1.05 eV for SBN, C 0.1 SBN and C 0.25 SBN ceramic, which are colse to the activation energy value of the ionic conductivity by oxygen vacancies in perovskite type ferroelectric oxides [28][29][30].…”