Device models for PZT/PT, BST/PT, SBT/PT, and SBT/BI ferroelectric memories

Abstract We have used x-ray photoelectron spectroscopy (XPS) and ultraviolet absorption measurements to determine unambiguous values of the electron affinities and band structure alignments for the three most popular ferroelectric memory materials (strontium bismuth tantalate SBT. lead zirconate-titanate PZT, and barium strontium titanate BST) on platinum electrodes. The PZT/Pt results and model disagree quantitatively and qualitatively with the earlier work of Wouters, Willems, and Maes [Microelectron. Eng. 29, 249 (1995)], who inferred an electron affinity of 2.6 eV, compared with our value of 3.5 eV. Nano-electrode fabrication is discussed for such memories, and nano-electrode interface models of SBT/Bi are included.