Strain Engineering Effects on Electrical Properties of Lead-free Piezoelectric Thin Films on Si Wafers

Abstract

Using radio frequency - magnetron sputtering, calcium-doped barium zirconate titanate ((Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃, BCZT) thin films were deposited on Si wafers with different bottom electrodes. The obtained BCZT thin film on a lanthanum nickel oxide (LNO) electrode had a highly c-axis preferred orientation, while the BCZT thin film on a Pt bottom electrode had (111) preferred orientation. Furthermore, the out-of lattice constant of the BCZT on LNO/Si was 3.4% larger than that of the reported bulk material because of the compressive thermal stress from LNO with a large thermal expansion coefficient. This compressive thermal stress engenders an increase of the Curie temperature. The local piezoelectric response of the BCZT thin film on a LNO/Si structure was measured by piezoresponse force microscope.