Perspective on Ferroelectric Devices: Lessons from Interfacial Chemistry

Ferroelectric fluorite-structured oxide thin films have attracted increased interest from both academia and industry because of their superior scalability─in which their ferroelectric properties can be maintained even below 10 nm thickness─and excellent compatibility with current complementary metal–oxide–semiconductor technology. Regarding recent efforts to downscale the technology node of semiconductor processing, the emergence of ferroelectric properties in fluorite-structured oxide thin films at small length scales is of particular interest. As the length scale of the fluorite-structured oxide thin films reaches the atomic scale, the contribution of the interfacial layer to the properties naturally increases. In particular, the quality and type of interfacial layer, as well as the reaction chemistry in response to the electric field, play a major role in determining the properties of the devices. Consequently, understanding the chemistry of ferroelectric–electrode and ferroelectric–semiconductor interfaces is crucial for their use in industrial applications in the near future. In this context, emerging semiconductor devices based on fluorite-structured oxide ferroelectrics, including ferroelectric field-effect transistors, ferroelectric random-access memories, and ferroelectric tunnel junctions, and the impact of interface chemistry in the devices are reviewed in detail.