Ferroelectric Domain Engineering Using Structural Defect Ordering

Abstract

Ferroelectrics have become indispensable in the development of energyefficient oxide electronics. Their domain state is closely linked to the final device functionality, making domain engineering in technology-compatible thin films of paramount importance. Here we demonstrate the local control of domain formation in two-dimensional epitaxial ferroelectric films using structural defect engineering through the substrate topography. Using a combination of first-principles calculations, atom probe tomography, and scanning probe microscopy, we show that out-of-phase boundaries induced at the substrate step edges combined with local off-stoichiometry trigger the formation of ferroelectric domain walls in the layered ferroelectric Bi 5 FeTi 3 O 15 Aurivillius thin films. The substrate treatment and the miscut angle selection allow for precise control of domain size and location in both single layers and multilayer architectures. With this work, we establish a new route for ferroelectric domain engineering and stabilization of functional domain walls in ultrathin ferroelectric layers.

Ferroelectric Thin Films for Oxide Electronics

“…The achievement of high-quality, twin-free films enabled the investigation of domain engineering in the Aurivillius materials. The first studies indicated the ability to control the formation of structural defects in the layered structure of the films using substrate morphology; see Figure d–g . The ordering of the so-called steric out-of-phase boundaries appears as key in the controlled formation of in-plane-polarized ferroelectric domains.…”

“…(h, i) Isosurfaces around an out-of-phase boundary in the Bi 5 FeTi 3 O 15 film containing a high Bi density. Panels d–i reproduced with permission from ref . Copyright 2022 by the American Chemical Society.…”

“…Only with the rather recent emergence of laser-assisted APT essentially all materials classesincluding insulators and complex oxideshave become accessible. The first studies dealing with ferroelectric systems have been reported recently. , The high chemical sensitivity of the APT provided insights into the cation segregation of PbZr 0.53 Ti 0.47 O 3 ceramics near the morphotropic phase composition . More recently, APT was applied to epitaxial ferroelectric Aurivillius thin films to elucidate the three-dimensional structure of out-of-phase boundaries, driving the in-plane-polarized domain formation in the films, as depicted in Figure g–i.…”

“…The first studies dealing with ferroelectric systems have been reported recently. , The high chemical sensitivity of the APT provided insights into the cation segregation of PbZr 0.53 Ti 0.47 O 3 ceramics near the morphotropic phase composition . More recently, APT was applied to epitaxial ferroelectric Aurivillius thin films to elucidate the three-dimensional structure of out-of-phase boundaries, driving the in-plane-polarized domain formation in the films, as depicted in Figure g–i. Furthermore, in the doped ferroelectric hexagonal manganite Er­(Mn,Ti)­O 3 it was possible to map the position of the Ti dopants despite their extremely low concentration of 0.04 at.…”

“…(d–g) Topography of the NdGaO 3 (001) substrate (d and f) determining the formation of ferroelectric domains, as depicted in the corresponding lateral-piezoresponse force microscopy images (e and g). Panels d–g reproduced with permission from ref . Copyright 2022 American Chemical Society.…”