Lead zirconate titanate thin films by aerosol plasma deposition: Microstructure analysis

Lead zirconate titanate (Pb(Zr,Ti)O-3, PZT) thin films were grown on silicon (100) substrate by aerosol plasma deposition (APD) using solid-state-reacted powder containing donor oxide Nb2O5 when keeping the substrate at room temperature and 200degreesC. Crystalline phases of the deposited films have been analyzed via X-ray diffractometry (XRD), and microstructure via scanning and transmission electron microscopy (SEM and TEM). Cross-sectional TEM revealed that the microstructure comprised several layers including the deposited PZT film and the platinum-electrode-and-titanium-buffered layers on SiO2-Si substrate. The Pt-electrode layer contained (111)(Pt) twinned columnar grains with a slight misorientation and forming low-angle grain boundaries among them. The PZT layer contained randomly oriented grains embedded in an amorphous matrix. Some of the PZT grains, oriented with the zone axis Z = [211](PZT) parallel to Z = [111](Pt), were grown epitaxially on the Pt layer by sharing the (111)(PZT) plane with the (111)(Pt) twinned columnar Pt crystals. However, the existence of such an orientation relationship was confined to several nanosize grains at and near the PZT-Pt interface, and no gross film texture has been developed. An amorphous grain boundary phase, generated by pressure-induced amorphisation (PIA) in the solid state, was identified by high-resolution imaging. Its presence is taken to account for the densification of the PZT thin films via a sintering mechanism involving an amorphous phase on deposition at 25degrees and 200degreesC.