Ferroelectric properties of (Bi, SM)(4)Ti3O12 (BST) thin films fabricated by a metalorganic solution deposition method

Abstract

Ferroelectric properties of samarium substituted Bi4Ti3O12 films, Bi3.15Sm0.85Ti3O12 (BST), were evaluated for use as lead-free thin film ferroelectrics for FeRAM applications. The BST films were fabricated on the Pt/Ti/SiO2/Si(100) substrates by a metalorganic solution deposition method. The measured XRD patterns revealed that the BST films showed only a Bi4Ti3O12-type phase with a random orientation. The BST film capacitors showed excellent ferroelectric properties. For the film capacitor annealed at 700degreesC, 2P(r) of 64.2 muC/cm(2) and 2E(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 x 10(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.