Effect of sputtering-target composition on the structure, dielectric, ferroelectric, and energy storage properties of highly (00l)-oriented Ba(Zr_xTi_1-x)O₃ films

It is relatively easy to obtain highly oriented/textured Ba(ZrxTi1-x)O-3 (BZT) films by magnetron sputtering, but it is complicated to control the composition of these sputtered oriented films. Here, a series of BZT ceramic targets with different ingredients (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) and a BaTiO3 (x = 0) target were fabricated by solid-state sintering. Then, the corresponding BZT thin films were deposited on LaNiO3 (LNO) buffered Pt/Ti/(001)Si substrates adopting radio-frequency magnetron sputtering. Benefit from the prefabricated (001)-LNO buffer layer and optimized BZT film preparation process, all BZT films exhibit highly (00l) preferred orientation. However, the degree of orientation, lattice parameter, dielectric properties, ferroelectric behaviors, and energy-storage characteristics are all highly dependent on the Zr content of BZT films sputtered by targets with the same composition. (00l)-oriented BZT films with relatively low Zr content have a better crystalline structure [narrower full width at half maximum (FWHM), larger grains]. It is also found that the rising of the Zr content in (00l)-oriented BZT films will result in a larger out-of-plane lattice parameter, and these results indicate that the doping amount of Zr will strongly change the heterointerface stress/strain states and the growth mode of the oriented films, and then effectively tailor their electric performances.