Characterization and properties of lanthanum-substituted bismuth titanate ferroelectric thin films for FeRAM application

摘要

In the paper, polycrystalline and c-orientated Bi/sub 3.4/La/sub 0.6/Ti/sub 3/O/sub 12/ (BLT) thin films with uniform composition and thickness were prepared on Si and Pt/Ti/SiO/sub 2//Si substrates using a modified sol-gel technique. X-ray diffraction (XRD) studies indicated the formation of the Bi-based layered structure for BLT. The microstructure and surface morphologies of thin films significantly vary with the type of substrates. The grain growth and orientation of BLT thin films in different substrates intensively affect on the ferroelectric properties. The remanent polarization (P/sub r/) of BLT thin films on Pt/Ti/SiO/sub 2//Si and Si substrates is about 1.23 /spl mu/C/cm/sup 2/ and 4.54 /spl mu/C/cm/sup 2/, respectively. The higher the c-axis orientation ratio of BLT films, the less the value of P/sub r/ is. The fatigue properties remain nearly constant after 1.44/spl times/10/sup 12/ switching cycles. It indicates that lanthanum-substituted bismuth titanate is a kind of candidate material for FeRAM application.