Ferroelectric Property of Ion Beam Enhanced Deposited Lithium Tantalate Thin Film

Abstract

The Ion Beam Enhanced Deposited (IBED) lithium tantalate (LiTaO3) thin film samples with Al/LiTaO3/Pt electrode structure were prepared on the Pt/Ti/SiO2/Si(100) and SiO2/Si(100) substrate respectively. The crystallization, surface morphology, ferroelectric property, and fatigue property of the prepared samples with the different annealed processes were investigated. The XRD measured results show that the prepared samples have the polycrystal structure of LiTaO3 with the preferred orientation of <012> and <104> located at the 2θ of 23.60 and 32.70 respectively. The SEM morphology analysis reveals the prepared film annealed at 550°C is uniform, smooth and crack-free on the surface and cross section. The ferroelectric property measured results show that the remanent polarization Pr of the samples annealed at different temperature almost increase with the electric field intensity stronger. The leakage current makes the hysteresis loop of the samples subjected to a strong measured electric filed difficult to appear the same saturation hysteresis loop as the single-crystal LiTaO3. The prepared samples annealed at 550°C have a Pr value of 11.5μC/cm2 when subjected to the electrical field of 400kV/cm. The breakdown voltage of the 587nm thick thin film sample is high as to 680 kV/cm. The fatigue property measured results show only 15.17% Pr drop of the prepared films annealed at 550°C appear after 5×1010 cycles polarized by the 10MHz sinusoidal signal with the peak-to-peak amplitude of 10 Volt. The ferroelectric properties of the prepared films meet the practical application requirements of charge response measurement of the LiTaO3 infrared detector owe to the Pr of the prepared films annealed at different temperature large beyond 10μC/cm2 when the prepared films subjected to a strong electric filed larger than 400 kV/cm. The experimental results also show that the surface morphology, the ferroelectric and fatigue properties of the IBED LiTaO3 thin films are significant better than those of the Sol-Gel derived LiTaO3 thin films.