Leakage current and relaxation characteristics of highly (111)-oriented lead calcium titanate thin films

Abstract

Highly (111)-oriented (Pb[sub 0.76]Ca[sub 0.24])TiO₃ (PCT) thin films were grown on Pt/Ti/SiO₂/Si substrates by a sol-gel process. The Au/PCT/Pt metal-insulator-metal film capacitor showed well-saturated hysteresis loops at an applied field of 800 kV/cm with remanent polarization (P[sub r]) and coercive electric field (E[sub c]) values of 18.2 µC/cm² and 210 kV/cm, respectively. The leakage current depended on the voltage polarity. At low electrical field and with Pt electrode biased negatively, the Pt/PCT interface exhibits a Schottky emission characteristics. The Au/PCT interface forms an ohmic contact. The conduction current when the Au electrode is biased negatively shows a space-charge-limited behavior. The dielectric relaxation current behavior of Au/PCT/Pt capacitor obeys the well-known Curie-von Schweidler law at low electric field. At higher fields, the currents have contributions to both dielectric relaxation current and leakage current.