Thickness dependence of structure, tunable and pyroelectric properties of laser-ablated Ba(Zr0.25Ti0.75)O3 thin films

Ba(Zr0.25Ti0.75)O-3 thin films are grown on LaNiO3-coated SiO2/Si substrates with thicknesses varying from 100 to 700 nm. The films show (00l)-preferred orientation which gradually decreases with an increase in (011) orientation due to competitions between interfacial energies and lattice constraint from LaNiO3 template. The out-of-plane lattice parameter d increases or relaxes towards the bulk value, causing a reduction in the in-plane tensile strain and a shift in the ferroelectric-paraelectric phase transition region to room temperature. Orientation, lattice strain and particularly the film/electrode interface are the reasons for the increased dielectric constant epsilon(r)(0) with thickness. The reduction in tensile strain in combination with enhancement in epsilon(r)(0) has resulted in an increase in tunability n(r), while the shift of phase transition region in combination with enhancement of epsilon(r)(0) in this region has resulted in an increase in pyroelectric coefficient p.