Influence of the Substrate Surface on the Self-Assembly of Ferroelectric PbTiO₃ Nanostructures Obtained by Microemulsion Assisted Chemical Solution Deposition

Abstract

The achievement of long range periodicity of ferroelectric nanostructures on substrates remains as a challenge in the processing of devices by the relatively inexpensive self-assembly methods. To this aim, here we make the proposal of processing strategies involving commercial single-crystal SrTiO ₃ (100) substrate surface treatment. The topography, global ordering and crystal symmetry of the surface of the treated substrates as well as the near surface layer composition were analysed by Scanning Force Microscopy, Low Energy Electron Diffraction and Auger Electron Spectroscopy, respectively. The study shows that a combination of chemical etching and thermal annealing in air produces smooth and well terraced surfaces which have steps of few unit cells height and a nearly complete TiO ₂ termination, while keeping the 1× 1 bulk structure. Preliminary results shows that PbTiO ₃ nanostructures, obtained by a novel microemulsion assisted Chemical Solution Deposition method onto such substrates, grow at regular distances and preferentially located at the edges of the substrate surface terraces. Thus, long range order of these nanostructures is envisaged when deposited onto substrates that are treated by the procedure here studied.

Acknowledgments

This work has been financed by the Spanish Projects MAT2007–61409 and MAT2004–05348-C04-02. M.Torres thanks to the Spanish Ministry of Science and Innovation for supporting her Ph.D grant of the FPI program. The authors also thank the support of NoE MIND CE FP6 515757-2, promoting the Piezoinstitute (European Institute of Piezoelectric Materials and Devices).