Nanoscale Design of High-Quality Epitaxial Aurivillius Thin Films

Efforts for the integration of ferroelectric materials in nonvolatile, low energy consuming memories have so far been focused on perovskite oxide materials. Their down-scaling for nanodevices is, however, hindered by finite-size effects, and alternative materials offering more robust polar properties are required. Layered ferroelectrics of the Aurivillius phase have since emerged as promising candidates with robust polarization at subunit-cell thicknesses. Their controlled growth in the epitaxial thin film form has unfortunately remained elusive. Here, we demonstrate the stabilization of the coalescent layer-by-layer growth mode of the Bin+1Fen-3Ti3O3n+3 (BFTO) Aurivillius family homologues. We define the growth conditions for high-quality, single-crystalline thin films exhibiting ferroelectricity from the first half-unit-cell. We demonstrate the process to be effective for several homologous Aurivillius compositions, which highlights its general applicability. Our work thus provides the systematic framework for the integration of high-quality epitaxial layered ferroelectrics into oxide electronics.

Automated summary

Efforts to integrate ferroelectric materials into nonvolatile, low energy consuming memories have focused on perovskite oxide materials. However, finite-size effects hinder their down-scaling for nanodevices, and alternative materials with robust polar properties are needed. Layered ferroelectrics of the Aurivillius phase have emerged as promising candidates with robust polarization at subunit-cell thicknesses, but controlled growth in epitaxial thin film form remains challenging. Here, the stabilization of coalescent layer-by-layer growth mode for Aurivillius family homologues is demonstrated, providing a systematic framework for the integration of high-quality epitaxial layered ferroelectrics into oxide electronics.