Crack resistance of bismuth ferrite films obtained on a flexible substrate

Ultrathin BiOx and FeOx layers were obtained by Atomic Layer Deposition (ALD) on the surface of a flexible Kapton substrate (poly (4,4’-oxydiphenylene-pyromellitimide)) at a temperature of 250 °C. The layer thickness was 50 - 100 nm. Surface morphology, electrical polarization, and mechanical properties were investigated by Atomic Force Microscope, Piezoelectric Force Microscopy and Force Modulation Microscopy. Chemical analysis was performed by X-ray Photoelectron Spectroscopy, where the formation of Bi2O3 and Fe2O3 phases, as well as intermediate phases in the Bi-Fe-O system, was observed. With a small increase in the Bi content of the film, the BFO / Kapton structure becomes more crack resistant. Modification of the Kapton surface with bismuth and iron oxides showed that such a composition exhibits multiferroic behavior