The Thermalstability of Voltage Tunability in Pulsed Laser Deposited Ba_0.6Sr_0.4TiO₃ Thin Films

Abstract

Temperature stability of voltage tunability and figure of merit (FOM) were investigated for the pulsed laser deposited Ba_0.6Sr_0.4TiO₃ (BST_0.6) thin films on platinum coated silicon [Pt(111)/TiOx/SiOx/Si(100)] substrates. The structural and micro-structural properties of these films were analyzed using x-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Metal-ferroelectric-metal (MFM) mono-dielectric layer stacks were fabricated using these films and their temperature and voltage dependent dielectric properties were quantified. The temperature dependence of dielectric properties were analysed using the modified Curie-Weiss law. The films showed a good dielectric tunability of about 40% at a bias field of 125 kV/cm. The determined figure of merits are found to be highly sensitive to the temperature changes. The observed ferroelectric-like behaviour in these films above the Curie point (T_c) has been attributed to the thermal expansion mismatch and the substrate induced misfit strain with the Pt/Si substrate.

Keywords:

• BST
• ferroelectric
• dielectric tunability
• thermal stability
• figure of merit
• diffused phase transition