Research progress and device applications of multifunctional materials based on two-dimensional film/ferroelectrics heterostructures

With the rapid development of microelectronic integration technology, the miniaturization, integration and multifunction of electronic devices are becoming a general trend. Two-dimensional materials are a class of layered material with atomic layer thickness, and have unique electrical, magnetic, optical and mechanical properties. The co-existence of the weak van der Waals force between layers and the strong covalent bonding within layers makes the two-dimensional material very suitable for the miniature design of new-generation multifunctional electronic devices. Two-dimensional materials, represented by graphene and transition metal chalcogenides, exhibit high mobility, adjustable energy band and high visible light transmittance, and thus having become the frontier hotspots in the field of micro-nanoscience in recent years. Synergy between two-dimensional materials and various functional materials such as SiO₂ insulator, semiconductor, metal and organic compound may lead to new properties and device applications, thus can deepen and expand the basic research and application of two-dimensional materials. Among them, ferroelectric materials have received much attention because of their spontaneous polarizations, high dielectric constants, and high piezoelectric coefficients. The two-dimensional ferroelectric composites well have the advantages of the two, i.e. they not only contain a variety of rich phenomena such as the magnetoelectric coupling effect, ferroelectric field effect and lattice strain effect, tunneling effect, photoelectric effect, and photoluminescence effect, but also have broad applications in devices such as multi-state memories, tunneling transistors, photoelectric diodes, solar cells, super capacitors, and pyroelectric infrared detectors, which have attracted wide concern from academia and industry. To better understand the combination of two-dimensional thin films with ferroelectric substrates and provide a holistic view, we review the researches of several typical two-dimensional film/ferroelectrics heterostructures in this article. First, two-dimensional materials and ferroelectric materials are introduced. Then, the physical mechanism at the interface is briefly illustrated. After that, several typical two-dimensional film/ferroelectrics heterostructures are mainly introduced. The ferroelectric materials including Pb(Zr_1–<i>x</i>Ti<i>_x</i>)O₃, (1–<i>x</i>)PbMg_1/3Nb_2/3O₃–<i>x</i>PbTiO₃, P(VDF-TrFE), are mainly summarized, and other ferroelectric materials such as P(VDF-TrFE-CFE), BaTiO₃, BiFeO₃, PbTiO₃, CuInP₂S₆, HfO₂ are briefly involved. The future research emphasis of the two-dimensional materials/ferroelectrics composites is also suggested at the end of the article. This review will present a significant reference to the future design of miniature and multifunctional devices.