Effect of top electrode thickness on the piezoresponse of polycrystalline ferroelectric capacitors

Abstract

The domain images of ferroelectric capacitors with different top electrode thicknesses in the as-grown and poled states were obtained by piezoresponse force microscopy (PFM). In poled capacitors, a uniform piezoresponse with the same contrast was obtained for top electrodes of different thicknesses. For capacitors in the as-grown state, a lower piezoresponse was observed with thicker top electrodes, due to the different domain orientations, suppression effect of the ferroelectric domains and the damping effect of the electrode. It is shown that the piezoresponse decreases nonlinearly with the increase in electrode thickness. When the top electrode thickness is above 75 nm, the piezoresponse value is almost zero. When the top electrode thickness is increased from less than 10 to 75 nm, the piezoresponse is reduced rapidly to a very small value. Details of the domain wall, grain boundary and defects gradually become indistinguishable. Our investigation suggests that to obtain clear domain information by PFM based on global excitation, the top electrode thickness should be less than 10 nm.

Atomic Origins of Enhanced Ferroelectricity in Nanocolumnar PbTiO3/PbO Composite Thin Films

“…The increased switching voltage and unswitchable spots in the PFM phase images are due to the increasing amount of non‐ferroelectric PbO in the composite thin film. [ 45,46 ] Furthermore, the second harmonic generation (SHG) study (Figure S11, Supporting Information) on an additional nanocolumnar PTO/PbO film also suggests the out‐of‐plane polarization, and its switching nature is confirmed by the PFM measurements as shown in Figure S12 (Supporting Information).…”

Piezoresponse in Ferroelectric Materials under Uniform Electric Field of Electrodes

“…The most straightforward PFM implementation is in the so-called “global excitation mode”, where an electric field is applied through micro- or nano-sized electrodes, while signal registration is performed utilizing scanning probe microscopy (SPM) probe rastering across the surface [ 16 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. Global excitation can be realized via an electric field applied to the conductive tip across the tip-electrode interface and simply by the excitation of the electrode with probe acting as a mechanical sensor.…”