Structural and electrical properties of rf-sputtered amorphous barium titanate thin films

Abstract

Structural and electrical properties of rf‐sputtered amorphous BaTiO₃ thin films grown on water‐cooled substrates have been investigated. The dielectric and electrical properties have been studied for films grown under varying sputtering gas composition (Ar+O₂ gas mixtures) as a function of film thickness, frequency, and temperature. As‐grown films were amorphous in nature and highly transparent. Post‐deposition annealing had no discernible effect either on film structure or dielectric properties, and there was no evidence of ferroelectricity. Films sputtered in pure argon showed a dielectric constant ε’∼12 with little dependence on frequency (0.1–100 kHz) over the temperature range 0–75 °C. The dielectric properties were a function of film thickness and the percentage of oxygen in the sputtering gas during growth. The thickness‐dependent dielectric properties of amorphous BaTiO₃ thin films on conducting glass substrates could be satisfactorily explained by a model based on the existence of electrode barriers. The high breakdown voltage (10⁶ V/cm), charge storage capacity (3.1 μC/cm²), and frequency‐ and temperature‐dependent dielectric properties of a‐BaTiO₃ films sputtered in pure argon show promise for application as insulating layers in thin‐film electroluminescent display devices.