Nanoscale properties of ferroelectric ultrathin SBT films

Strontium bismuth tantalate (SBT) ultrathin films with thickness about 40 nm have been prepared by a chemical solution deposition (CSD) method based on the synthesis of a Ta-glycolate derivative. Layers of the precursor solution diluted with 2-ethyl-1-hexanol were spin-coated onto Pt/TiO2/SiO2/(100)Si substrates. Crystallisation was carried out in oxygen at 650 °C by Rapid Thermal Processing (RTP). Topography of the films was observed by Scanning Force Microscopy (SFM). The piezoresponse mode of the SFM equipment was used to perform the nanoscale observation of the ferroelectric domain structure of the SBT ultrathin films and to measure piezoelectric hysteresis loops. The macroscopic ferroelectric response was measured on capacitors prepared after the deposition on the film surfaces of top platinum electrodes of ∼0.05 mm2 of area.