Enhancing ferroelectrics with insulators: Band offsets at the Al2O3/BaTiO3 interface

Engineering ferroelectric interfaces is key to improving device performance. Combining thin insulators with ferroelectrics is a promising approach for minimizing leakage currents and increasing the switching efficiency. In this work, we study the interface between atomic layer deposited amorphous Al2O3 and epitaxial BaTiO3 films. These materials constitute simple and robust examples of an insulator and a ferroelectric, respectively. We confirm the microstructure and interface chemistry of the heterostructure. X-ray photoelectron spectroscopy was employed to quantify the interfacial band offsets, yielding energy barriers of 1.3 eV for holes and 2.1 eV for electrons. These results highlight Al2O3 as a promising candidate for an insulating layer on ferroelectrics, paving the way for efficient insulator-ferroelectrics structures for ferroelectric functional devices.