Top electrode size effect on hysteresis loops in piezoresponse force microscopy of Pb(Zr,Ti)O3-film on silicon structures

Abstract

Experimental and theoretical studies of hysteresis loops in piezoresponse force microscopy (PFM) directed on elucidating the influence of top electrode lateral sizes on loop peculiarities were performed for Pt/Pb(Zr, Ti)O 3 /Pt/TiO x /SiO 2 /Si-substrate structures. The set of top Pt electrodes (50 nm to 10 lm of lateral size) was deposited on the Pb(Zr x Ti 1Àx )O 3 film (x ¼ 0.54, thickness %1 lm) by RF magnetron sputtering. Under approaching the top electrode lateral size to the film thickness, the transition-like behaviour of PFM response amplitude and coercive tip voltage was observed. The existence of the critical value of dimensionless electrode size parameter cd/h % 1 (c is the dielectric anisotropy factor, d is the electrode size parameter, and h is the film thickness) was interpreted in the framework of the model based on Landau-Ginzburg-Devonshire theory combined with the decoupling approximation subject to the nonlinear electric field dependence of the ferroelectric polarization and dielectric permittivity. V

Top electrode size effects in the piezoresponse force microscopy of piezoelectric thin films attached to a rigid substrate

“…The electric charge is dramatically increased while the effective piezoelectric coefficient is greatly suppressed and they both transfer from the HS solutions to the IT results when / a t varies from 0.001 to 20. And a transition-like behavior between the HS and IT cases is also observed at about / a t=1 as reported in the experimental research of Bravina et al [13]. Then a critical top electrode size, i.e., > / a t 10, is obtained and applicable to other piezoelectric materials.…”

“…And for large electrode size, e.g., 1.2 μm, the effective piezoelectric coefficient decreases to a constant. This size effect and transition-like behavior have also been reported by Bravina et al [13] investigating the piezoresponses of PZT films with different top electrode radii. Wang et al [16] studied the electrode size effects using finite element analysis and found that for pads less than a few mm the displacement of the top surface is greatly reduced.…”

“…The surface deformation is then monitored by the AFM tip [8][9][10]. The advantage of this method consists of a relatively uniform electric field and surface deformation, thus is preferentially used to detect piezoelectric coefficients [11][12][13].…”

Ultrathin Ferroelectric Films: Growth, Characterization, Physics and Applications

“…It is noteworthy that recent phenomenology and first-principle calculations have demonstrated that asymmetric electrodes could lead to distinguished ferroelectric size effect, imprint behaviors, and novel properties (e.g., dielectric behavior and electron transport) in ferroelectric thin films from their symmetric counterparts, such as smearing of the phase transition, an induced piezoelectric response above T c , and reversal of the polarization asymmetry by application of biaxial strain etc. , which should be further verified experimentally (e.g., via x-ray diffraction analysis) [ 252 , 299 , 308 , 309 , 310 , 311 , 312 , 313 ]. To be more clear, we would like to take the theoretical research of Zheng et al [ 311 ] as an example, where asymmetric ferroelectric capacitors (A-FCs) with a single-domain ferroelectric thin film (FTF) sandwiched between different electrodes has been investigated ( Figure 9 a).…”

Preface to Special Topic: Piezoresponse Force Microscopy and Nanoscale Phenomena in Polar Materials

“…54 A number of authors investigate the image formation mechanism in PFM. The size effect on PFM is studied by Bravina et al, 55 continuing a series of detailed work on mathematical underpinning of PFM signal under various conditions. Reconstruction of domain structures from PFM data is nicely elaborated by Li et al 56 Finally, the significant effort is devoted to the role of surface electrochemical processes on polarization dynamics as determined by PFM.…”