Review of orientation-microstructure-property relationships for PZT/metal or metal-oxide layered heterostructures

Studies performed by our group on orientation-microstructure-property relationships of Pb(ZrxTi1-x)O3 (PZT)/metal or metal-oxide layered heterostructure are reviewed. The work discussed is related to the synthesis and characterization of ferroelectric PZT and conductive Pt, RuO2, and La0.5Sr0.5CoO3 layers and their integration into heterostructure capacitors suitable for non-volatile memories. The main objective of our research was to determine the influence of deposition techniques and their related parameters and layer processing on the orientation, microstructure, and properties of PZT-based capacitors, with the goal of controlling electrical properties such as polarization fatigue, retention, and imprint effects, in order to produce commercial non-volatile ferroelectric memories. The work discussed relates to the synthesis of films by ion beam sputter-deposition (IBSD), and pulsed laser ablation deposition (PLAD), where the heterostructures are grown in-situ without exposing the interfaces to uncontrollable atmospheric conditions. Comparisons are presented between orientation and microstructural characteristics and properties of PZT heterostructure capacitors produced by IBSD and PLAD and those synthesized by the sol-gel technique. The work reviewed indicates that substrate and template layers (at the ferroelectric/bottom electrode interface) and/or bottom electrode material type contribute to the control of orientation and/or microstructure, and properties of PZT-based capacitors.