Giant tunneling electroresistance in epitaxial ferroelectric ultrathin films directly integrated on Si

Retaining information with the least loss of energy is of interest for ubiquitous mobile devices. Various forms of nonvolatile memory have been pursued based on the resistance change in the memory architecture. The nonvolatility of spontaneous polarization in a ferroelectric material also has been considered a promising ingredient for information storage applications, including traditional nonvolatile memory applications and emerging neuromorphic synaptic devices. Here, we demonstrate a colossal resistance change in the ferroelectric tunnel junction with an On/Off ratio of 106 in a ferroelectric HfO2 thin film integrated directly on a silicon wafer, which is inevitable for practical application. To achieve this large On/Off ratio, we integrated the epitaxial fluorite-structure HfO2 thin film on the silicon substrate. The polarization direction in the metal-ferroelectric-semiconductor junction altered the depletion width, leaving behind the change in the tunnel barrier. Industry-relevant HfO2 with high CMOS compatibility could lead to fast adoption of a ferroelectric tunnel barrier with newly observed ferroelectricity in fluorite-structured HfO2 films.