Investigation On Barrier Layers Of PT/BaTiO₃/PT Based Thin Film Capacitors

Abstract

Barium titanate is a ferroelectric material used as a dielectric in thin film capacitors owing to its high dielectric constant. Barrier layers are utilized in these capacitors to improve the capacitors' performance. In this paper, zinc oxide and aluminium oxide are kept on both sides of BaTiO3 as barrier layers in Pt/BT/Pt capacitors and different dielectric properties are studied. The parameters such as capacitance density, leakage current, ESR, dielectric loss and dielectric strength of Pt/BT/Pt capacitors with barrier layers of different sizes are simulated using COMSOL Multiphysics modeling software. Aluminum oxide of 2 nm thickness as a barrier layer gives optimal performance. The leakage current, dielectric loss, capacitance density, equivalent series resistance and dielectric strength of Pt/BT/Pt capacitor are found to be 0.519 mA, 9.62x10‐12, 172.8 fF/µm2, 9.62 kΩ, 108 V/m respectively whereas that of Pt/ALO/BT/ALO/Pt capacitor are found to be 1.56x10‐18A, 7.81x10‐18, 11.6 fF/µm2, 9.01x1015 Ω, 5.05x109 V/m respectively. The low capacitance in Pt/ALO/BT/ALO/Pt capacitor is due to the low dielectric constant of Al2O3 layer. The reduced leakage current and increased equivalent series resistance is due to the low conductivity of the Al2O3 layer. The use of aluminium layer can reduce the electric field leading to improved dielectric strength.