The reliability properties of MOCVD PZT thin films on multilayer PT/IR electrodes

Abstract

The reliability properties including fatigue, thermal stability, thermal imprint and retention properties of PZT thin films on multilayer Pt/Ir electrodes have been investigated. An oxide MOCVD reactor with liquid delivery system was used for the growth of PZT thin films. The experimental results showed that the PZT thin films on <111> oriented multilayer Pt/Ir electrodes exhibited excellent reliability properties. The normalized polarization of PZT thin films on Pt/Ir electrodes was about 50% after 1 × 10¹⁰ switches at switching frequency of 5 kHz and switching voltage of 5 V. When the temperature is increased from 28°C to 120°C, the 2Pr values is reduced from 40.2 μC/cm² to about 32.2 μC/cm². The 2Ec value decreases from 74.4 kV/cm to 61.3 kV/cm at a switch voltage of 5 V. The leakage current of the PZT thin films increased from 1.7 × 10⁻⁷ A/cm² to 5.5 × 10⁻⁶ A/cm² at 100KV/cm with increasing the temperatures from 28°C to 120°C. Based on these data the dc activation energy is about 3.7 eV, which is much higher than that of other ferroelectric material. The dielectric constant of the PZT thin films showed the similar behavior to the most ferroelectric materials. At temperatures lower than Curie temperature the dielectric constants of PZT thin films increases with increasing temperature. The dielectric constant of the PZT thin films is about 1400 at 120°C. The PZT thin films on <111> oriented multilayer Pt/Ir exhibit excellent imprint and retention properties.

Key Words:

• Ferroelectrics
• PZT
• Thin film
• MOCVD