Modifying energy storage performances of new lead-free system ferroelectric capacitors through interfacial stress

Abstract

Ferroelectric energy storing is one of the most potential research hotspots in functional materials. To seek for better performance, current strategies are mostly relied on structure designing and multi-element (more than 5) doping. Till now, energy storage density (ESD) for ferroelectric thin film capacitors have reached to over 100 J/cm3, which seems to be a bottleneck, and the corresponding material structure and chemical composition are also becoming complex. Thus, exploiting simple and single-layered candidates will probably re-develop this field. For epitaxial thin films, interfacial stress from substrates will assist. Hence, a new system of Sm doped BaZr0.2Ti0.8O3 (BaZr0.2Ti0.8O3-2%Sm2O3, abbr. BZTS) thin films were epitaxially grown on STO substrates and a better ESD of 40.42 J/cm3 with η of 85.03% was obtained in 200-nm film. The effects of interfacial stress between films and substrates on the ferroelectric performance of BZTS thin films have been systematically discussed. The interfacial pressure stress offered by substrates enhanced the thermal stability and Sm doping facilitated the ferroelectric behavior. Finally, this new BZTS system thin films shown rather a better ferroelectric reliability in both temperature and frequency than the only-BZT system, making it a proper candidate to be composited with other materials in next-generation functional materials.