Critical thickness for extrinsic contributions to the dielectric and piezoelectric response in lead zirconate titanate ultrathin films

Abstract

Thickness effect on the dielectric, ferroelectric, and piezoelectric properties of ferroelectric lead zirconate titanate thin filmsHighly ͑100͒-textured Pb͑Zr 0.53 Ti 0.47 ͒O 3 films ͑Lotgering factors Ն90%͒ with thicknesses ranging from 20 to 260 nm were grown on platinized Si substrates using sol-gel deposition. Ferroelectric hysteresis, low field dielectric permittivity, and nonlinear dielectric response as well as converse longitudinal piezoelectric response ͑d 33,f ͒ of the ultrathin films were studied at 1 kHz. The measurements revealed the existence of a critical film thickness, ϳ50 nm, below which the extrinsic contributions to the dielectric response are almost completely suppressed. Piezoelectric response of the films also showed a significant ͑ϳ50%͒ drop at the same critical thickness. Due to the columnar microstructure of these films the critical dimension of the ferroelectric is represented by the thickness rather than the lateral grain size, where the latter is invariant across the samples. The critical thickness led also to a deviation of the thickness dependence of the dielectric permittivity from the in-series capacitors model frequently representing "interfacial dead layers." The critical size is attributed to significant reduction in domain wall population and/or mobility in films thinner than ϳ50 nm.

The effect of Mg doping on the dielectric and tunable properties of Pb0.3Sr0.7TiO3 thin films prepared by sol–gel method

“…The domain wall motion contributions to the dielectric nonlinearity and polarization in subswitching fields can be described by the Rayleigh law [10,29],…”

Local Probing of Ferroelectric and Ferroelastic Switching through Stress‐Mediated Piezoelectric Spectroscopy

“…The initial topography image in Figure 1a highlights the polycrystalline nature of the film, which consists of (100) textured grains (Supplementary Information Figure S.1). [28] Assuming that an increase in the out-of-plane polarization component of the domains makes the film more amenable to subsequent ferroelastic switching under applied normal load, a region was written with an electric bias of -6 V, applied from the tip. Vertical PFM amplitude and phase images (Figures 1b and 1d) indicate clear polarization switching in the electrically-written region.…”

“…Based on XRD data reported elsewhere, less than ~3% departure from (100) orientation is expected in the studied films. [28] A more probable alternative involves a phase transition under mechanical load, based on the proximity to the MPB. Specifically, a transition from rhombohedral to tetragonal phase "a" domain (R → Ta), such as that seen in the phase field simulations (Figure 5e), can be expected under the applied normal load.…”

“…The full description of the processing procedure for the substrate, films and electrodes is provided elsewhere. [28] Functional Characterization. The mechanical writing was performed by increasing the deflection set-point (i.e.…”

Applications of piezoresponse force microscopy in materials research: from inorganic ferroelectrics to biopiezoelectrics and beyond

“…6,7 In this context, the advent of atomic force microscopy (AFM) techniques and their ability to probe matter with nanometric lateral resolution has allowed the physical limits of electromechanical phenomena to be explored. [8][9][10][11][12] AFM has been instrumental in ushering in the age of nanotechnology owing to its high resolution and sensitivity across a range of interaction forces, allowing AFM to find applications in materials science, physics, chemistry, and biology. 13 Initially developed to map surface topography of materials, 14 various modalities were subsequently developed to probe, e.g., mechanical, magnetic, electrical, and chemical properties.…”