Characteristics of (La_1−xSr_x)MnO₃ and (La_1−xSr_x)CoO₃ buffer materials and their effect on ferroelectric properties of (Pb_1−xSr_x)TiO₃ thin films

Abstract

The performance of new buffer materials, (La_0.5Sr_0.5)MnO₃ (LSMO) deposited on uncoated or Pt-coated silicon substrates by pulsed laser deposition process was systematically investigated and was compared with those of (La_0.5Sr_0.5)CoO₃ (LSCO) materials. Perovskite LSMO and LSCO thin films can be obtained by depositing the materials at 500–700°C substrate temperature (in 0.02–10.00 mbar oxygen pressure), regardless of substrate materials. LSMO/Pt (or LSCO/Pt) double layer electrode materials possess pronouncedly smaller electrical resistivity than those of LSMO (or LSCO) single layer electrode materials and, thereafter, are more suitable for applying as buffer layers for the synthesis of (Pb_0.6Sr_0.4)TiO₃ (PSrT) thin films. PSrT/LSMO/Pt(Si) thin films have ferroelectric properties as good as LSCO-buffered PSrT thin films. They own dielectric constant k≅3000, remanent polarization P_r =18 − 20 μC/cm² and coercive field E_c =44.6 − 51.4 kV/cm. However, LSMO electrode materials perform more satisfactorily due to better handling endurance of PSrT/LSMO/Pt(Si) thin films during post-processing for device fabrication.

Keywords:

• polarization
• ferroelectrics
• buffer layer