Substrate effects on domain structures of PZT 30/70 sol-gel films via PiezoAFM

Using an atomic force microscope (AFM) modified to perform PiezoAFM we have investigated the piezoelectric response of sol-gel thin film lead zirconate titanate (PZT 30/70, PbZr0.3Ti0.7O3) on Pt–Ti/SiO2/Si, indium tin oxide (ITO)/glass and Pt/MgO. The films were produced by spin coating a PZT 30/70 sol and firing at 520 °C for Pt electrode systems and 600 °C for the ITO system. By conducting PiezoAFM hysteresis loops we have shown that the localised piezoelectric response varies for PZT on differing substrates. The degree of asymmetry in the hysteresis loops varies for each substrate, as do the coercive fields. The coercive fields have been found to be ±18 V/μm for PZT/ITO/glass, +22 and −18 V/μm for PZT/Ti-Pt/SiO2/Si and +35 and −20 V/μm for PZT/Pt/MgO. The PZT grown on Pt/MgO, Pt-Ti/SiO2 and ITO/glass shows an offset or asymmetric hysteresis loop, which was confirmed by the differing fields required for poling during domain modification experiments performed on PZT/Pt/MgO. δ33 values obtained for the PZT thin films investigated range from 50pm/V for PZT/Pt–Ti/SiO2/Si to 40 pm/V for PZT/ITO/glass.