High pyroelectric Ba0.65Sr0.35TiO3 thin films with Ba0.65Sr0.35RuO3 seeding-layer for monolithic ferroelectric bolometer

Ba_0.65Sr_0.35TiO₃ (BST) thin films were deposited by RF sputtering with a very thin Ba_0.65Sr_0.35RuO₃ (BSR) seeding-layer on Pt/Ti/SiO₂/Si substrate. The crystallization of BST thin films and the surface morphology of BSR seeding-layer were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. XRD patterns show that the BSR seeding-layer affected the orientation of BST thin film, which is highly a-axis textured. It was also found that the BSR seeding-layer had a marked influence on the dielectric properties of BST thin films. Comparing with BST thin films directly deposited on Pt electrode, the dielectric relaxation can be suppressed and dielectric constant increased due to a possible reduction of interface oxygen vacancies at BST/BSR interface. Moreover, J–V measurement indicates that the leakage current density of BST thin films on BSR seeding-layer were greatly reduced compared with that of BST thin films directly on Pt electrodes. The pyroelectric coefficient of BST thin films with BSR seeding-layer is 7.57 × 10⁻⁷ C cm⁻² K⁻¹ at 6 V/μm at room temperature (RT). Our results reveal that high pyroelectric property of BST thin film could be achievable using BSR seeding-layer as a special buffer.