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 by controlling the microstructure and creating thin resistive films. In this paper, the effect of barrier layers in Pt/BT/Pt capacitors is studied using zinc oxide and aluminium oxide. The performance parameters such as capacitance density, leakage current, equivalent series resistance, dielectric loss and dielectric strength of Pt/BT/Pt thin film capacitors with barrier layers of different sizes are simulated using COMSOL Multiphysics modeling software. 2 nm thick aluminum oxide as Pt - BT 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, 9.62×10⁻¹², 172.8 fF/μm², 9.62 kΩ, 10⁸ V/m respectively whereas that of Pt/ALO/BT/ALO/Pt capacitor are found to be 1.56×10⁻¹⁸ A, 7.81×10⁻¹⁸, 11.6 fF/μm², 9.01×10¹⁵ Ω, 5.05×10⁹ V/m respectively. The low capacitance in Pt/ALO/BT/ALO/Pt capacitor is due to the low dielectric constant of aluminium dioxide barrier layer. The reduced leakage current and increased equivalent series resistance is due to the low conductivity of the aluminium oxide barrier layer. The use of aluminium oxide barrier layer between the conductive surfaces can reduce the electric field and increase the breakdown voltage, leading to improved dielectric strength and reduced dielectric loss.