THE PIEZOELECTRIC PZT THIN FILMS DEPOSITED ON METAL SUBSTRATES

In this study, we deposited PZT thin films directly on various kinds of metal substrates by rf-magnetron sputtering, and measured their crystal structure, and ferroelectric and piezoelectric properties. We used metal substrates of austenitic stainless steel (ASS), ferritic stainless steel (FSS), Ti, Ni, Zr and W for the PZT deposition. From the x-ray diffraction (XRD) measurements, we confirmed the PZT thin film was directly grown on each substrate with a perovskite phase. The dielectric constant of the PZT thin films showed obvious dependence on the coefficient of thermal expansion (CTE) of substrates. This result suggests that the dielectric constant, which is one of the important parameters for the piezoelectric vibration energy harvesters (PVEHs), can be controlled by the CTE of the substrates. The PZT film deposited on the FSS showed the best piezoelectric coefficient e(31,f) of -2.4 [C/m(2)], which was comparable to that of the PZT film formed on the platinum-coated metal substrates.