Effect of manganese doping on the size effect of lead zirconate titanate thin films and the extrinsic nature of dead layers

TL;DR

This study demonstrates that manganese doping in PZT thin films can significantly reduce and nearly eliminate the size effect, revealing its extrinsic nature linked to interfacial dead layers, with implications for ferroelectric device design.

Contribution

It provides experimental evidence that the size effect in ferroelectric thin films is extrinsic and can be mitigated by manganese doping, clarifying the role of dead layers.

Findings

Size effect reduced with increased Mn doping

Interfacial dead layer disappears at 2% Mn doping

Supports the extrinsic origin of the size effect

Abstract

We have investigated the size effect in lead zirconate titanate (PZT) thin films with a range of manganese (Mn) doping concentrations. We found that the size effect in the conventional Pt/PZT/Pt thin-film capacitors could be systematically reduced and almost completely eliminated by increasing Mn doping concentration. The interfacial layer at the electrode-film interface appears to disappear almost entirely for the PZT films with 2% Mn doping levels, confirmed by the fits using the conventional in-series capacitor model. Our work indicates that the size effect in ferroelectrics is extrinsic in nature, supporting the work by Saad et al. Other implications of our results have also been discussed. By comparing a variety of experimental studies in the literature we propose a scenario that the dead layer between PZT (or barium strontium titanate, BST) and metal electrodes such as Pt and Au might have a defective pyrochlore/fluorite structure (possibly with a small portion of ferroelectric perovskite phase).