Structural characterisation of BaTiO3 thin films deposited on SrRuO3/YSZ buffered silicon substrates and silicon microcantilevers

We report on the progress towards an all epitaxial oxide layer technology on silicon substrates for epitaxial piezoelectric microelectromechanical systems. (101)-oriented epitaxial tetragonal BaTiO3 (BTO) thin films were deposited at two different oxygen pressures, 5.10−2 mbar and 5.10−3 mbar, on SrRuO3/Yttria-stabilized zirconia (YSZ) buffered silicon substrates by pulsed laser deposition. The YSZ layer full (001) orientation allowed the further growth of a fully (110)-oriented conductive SrRuO3 electrode as shown by X-ray diffraction. The tetragonal structure of the BTO films, which is a prerequisite for the piezoelectric effect, was identified by Raman spectroscopy. In the BTO film deposited at 5.10−2 mbar strain was mostly localized inside the BTO grains whereas at 5.10−3 mbar, it was localized at the grain boundaries. The BTO/SRO/YSZ layers were finally deposited on Si microcantilevers at an O2 pressure of 5.10−3 mbar. The strain level was low enough to evaluate the BTO Young modulus. Transmission el...