Piezoelectricity in two-dimensional (2D) materials is increasingly important because of its potential in realizing thin yet efficient and flexible piezoelectric devices. In contrast to traditional three-dimensional (3D) piezo- and ferroelectrics that are prone to size effects, piezoelectricity in 2D materials may be controlled by flexoelectricity and interfaces thus providing significant piezoelectric effect in ultrathin films and crystals. Equally important, the majority of 2D layered piezoelectrics found so far possess in-plane piezoelectricity and require bending of flexible substrates to activate piezoelectric effect. This severely limits their integration with modern Si technology. This project aims at strengthening the piezoelectric activity in 2D materials via interface and stress engineering and bond control in order to reach the maximum efficiency and other relevant figures of merit. The materials list includes hafnium-zirconium oxide (HZO), transition metal thio/selenophosphates (TPS), graphene on oxide substrates, and polymer PDVF.
