Variable Size and Shape Distribution of Ferroelectric Nanoislands by Chemical Mechanical Polishing

Abstract

Ferroelectric PbTiO3 nanostructures with lateral dimensions typically below 100 nm are grown on platinized silicon substrates by a chemical solution deposition (CSD) technique. Chemical mechanical polishing allows control of the aspect ratio of the grains, since their initial size distribution is thermodynamically driven (see SEM images; above: as grown, below: polished). Piezoresponse force microscopy measurements on a 15‐nm‐thick PbTiO3 grain indicate that the polishing step has no detrimental effect on ferroelectric properties.

Electromechanical Imaging and Spectroscopy of Ferroelectric and Piezoelectric Materials: State of the Art and Prospects for the Future

“…It was supposed that this could be the limiting size for the ferroelectric phase. Recently Clemens et al 249 . reported on ferroelectricity in PbTiO 3 grains as small as 15 nm.…”

“…This instability leads to the formation of single crystal islands instead of continuous films. This process, which is normally undesirable was adapted by Waser and colleagues to grow separated 3D nanograins of PbTiO 3 on Pt(111)/TiO 2 /SiO 2 /Si substrates 150,248,249 . By controlling the sol–gel process, i.e.…”

“…This process, which is normally undesirable was adapted by Waser and colleagues to grow separated 3D nanograins of PbTiO 3 on Pt(111)/TiO 2 /SiO 2 /Si substrates. 150,248,249 By controlling the solgel process, i.e. the concentration of the stock solution, different grain sizes and grain size distributions, ranging from 200 nm to about 10 nm in diameter and 20 nm down to 2 nm in height were obtained.…”

“…It was supposed that this could be the limiting size for the ferroelectric phase. Recently Clemens et al 249 reported on ferroelectricity in PbTiO 3 grains as small as 15 nm. In this case the authors applied LPFM mode, which generally exhibits a higher resolution and a better signal/noise ratio than the VPFM mode.…”

Direct Observation of Core–Shell Structures in Individual Lead Titanate Ferroelectric Nanostructures by Tip‐Enhanced Refractive Index Mapping

“…In the quest to integrated laterally confined ferroelectric nanostructures without need for reactive ion beam etching (RIBE) or focused ion beam (FIB) treatment, Bühlmann et al, and Clemens et al suggested a seed‐mediated approach for the growth of lead titanate (PbTiO 3 ) nanoislands based on an e‐beam lithography pattern with unprecedented lateral dimensions down to a few tens of nanometers, penetrating into the realm of finite size effects. The direct investigation of these and other ferroelectric structures remained challenging and always related to measurements of an ensemble, which introduces additional uncertainties about the size distribution and other parasitic effects including domain wall contributions or the coupling of grains. Roelofs et al suggested that the loss of observable piezoresponse from nanostructures was an indication of the superparaelectric limit; however, reasonable doubts about the contact quality in piezoresponse force microscopy and the validity of the conclusion called for a contact‐free method for the investigation of individual nanoscale ferroelectrics.…”