Three-dimensional high-resolution reconstruction of polarization in ferroelectric capacitors by piezoresponse force microscopy

Abstract

Nemanich, R. J.; and Cross, J. S., "Three-dimensional high-resolution reconstruction of polarization in ferroelectric capacitors by piezoresponse force microscopy" (2004 A combination of vertical and lateral piezoresponse force microscopy ͑VPFM and LPFM, respectively͒ has been used to map the out-of-plane and in-plane polarization distribution, respectively, of ͑111͒-oriented Pb(Zr,Ti)O 3 -based ͑PZT͒ ferroelectric patterned and reactively-ion-etched capacitors. While VPFM and LPFM have previously been used to determine the orientation of the polarization vector in ferroelectric crystals and thin films, this is the first time the technique has been applied to determine the three-dimensional polarization distribution in thin-film capacitors and, as such, is of importance to the implementation of nonvolatile ferroelectric random access memory. Sequential VPFM and LPFM imaging have been performed in poled 1 ϫ1.5 m 2 PZT capacitors. Subsequent quantitative analysis of the obtained piezoresponse images allowed the three-dimensional reconstruction of the domain arrangement in the PZT layers of the capacitors. It has been found that the poled capacitors, which appear as uniformly polarized in VPFM, are in fact in a polydomain state as is detected by LPFM and contain 90°domain walls. Despite the polycrystallinity of the PZT layer, regions larger than the average PZT grain size are found to have the same polarization orientation. This technique has potential for clarifying the switching behavior and imprint mechanism in micro-and nanoscale ferroelectric capacitors.

Dynamic behaviour in piezoresponse force microscopy

“…30,31 This approach was further extended to 3D PFM imaging, in which both in-plane components of the response vector are determined with the out-of-plane component. 30,32 Note that measurement of the electromechanical response vector, as opposed to the qualitative data, is impossible unless the vertical and lateral signals are properly calibrated, i.e. measured in the same units.…”

Nanoscale characterization of β-phase HxLi1−xNbO3 layers by piezoresponse force microscopy

“…18,19 Furthermore, it can enable 3D reconstruction of the spontaneous polarization by combining vertical and lateral PFM, 20 estimation of piezoelectric coefficients, 21 and nanoscale characterization of ferroic samples with proton in-diffusion. 16,22 In this work, we present a coherent study on selectively proton-exchanged LN substrates, demonstrating the viability of a PFM approach for non-destructive high-resolution imaging of the PE regions.…”

Materials contrast in piezoresponse force microscopy

“…1,2,3,4,5 The ability to image ferroelectric domain structures with a nanometer resolution, relative insensitivity to the topographic cross-talk, and the capability to probe local switching behavior necessitate quantitative interpretation of the PFM signal in terms of the relevant material properties. Rigorous calculation of the electromechanical response induced by the biased tip requires the solution of the coupled electromechanical indentation problem, currently available only for the transversally isotropic case.…”