Structural and electrical properties of Ba_0.6 Sr_0.4 TiO₃ thin film on LNO/Pt bottom electrode

Ba_0.6 Sr_0.4 TiO₃ thin films are potential candidates for ferroelectric devices like Dynamic Random Access Memory (DRAM), microwave tunable devices, uncooled infrared detectors etc. For all such applications it is highly desirable to have BST film with lowest possible loss and leakage current with frequency independent dielectric properties. It is reported that bottom electrode of BST capacitor has high influence on such properties. In the present work, Ba_0.6 Sr_0.4 TiO₃ thin films were deposited on LNO/Platinum layered bottom electrode on a Silicon wafer. Both LNO and BST were deposited using Chemical Solution Deposition method. For comparative study, BST films were also deposited on Pt electrode. The structural properties were investigated using X-Ray Diffraction and Atomic Force Microscopy. Electrical properties were studied using impedance analysis and IV characterization of the stacks. Both the films were found to be polycrystalline with smooth and crack-free surface. Electrical characterization revealed low leakage current behavior with nearly frequency independent dielectric properties for BST films deposited on LNO/Pt electrode compared to a pure metallic Pt electrode. The LNO/Pt layered bottom electrodes are thus found to be well-suited for low-loss, low-leakage current ferroelectric device development.