Ferroelectric Properties of (Bi,Sm){sub}4Ti{sub}3O{sub}12 (BST) Thin Films Fabricated by a Metalorganic Solution Deposition Method

摘要

Ferroelectric properties of samarium substituted Bi{sub}4Ti{sub}3O{sub}12 films, Bi{sub}3.15Sm{sub}0.85Ti{sub}3O{sub}12 (BST), were evaluated for use as lead-free thin film ferroelectrics for FeRAM applications. The BST films were fabricated on the Pt/Ti/SiO{sub}2/Si(100) substrates by a metalorganic solution deposition method. The measured XRD patterns revealed that the BST films showed only a Bi4Ti{sub}3O{sub}12-type phase with a random orientation. The BST film capacitors showed excellent ferroelectric properties. For the film capacitor annealed at 700℃, 2P{sub}r of 64,2 μC/cm{sup}2 and 2E{sub}c of 101.7 kV/cm at applied electric field of 150 kV/cm were observed. The capacitor did not show any significant fatigue up to 1.5 × 10{sup}8 read/write switching cycles at a frequency of 1 MHz, which suggests that the samarium should be considered for a promising lanthanide elements to make a good thin ferroelectric film for memory applications.