Unique Polarization Switching of Wurtzite Ferroelectrics

Wurtzite (Al,Sc)N bas been utilized as microwave resonator and filter devices in telecommunications due to its large electromechanical coupling. The recent discovery of ferroelectricity in (Al,Sc)N films provides opportunities for device applications such as tunable filters and non-volatile memories. In this talk, I will present unique polarization reorientation behaviors of the wurtzite ferroelectric material: (1) strain insensitivity to the switching energy barrier and coercive field based on Landau-Devonshire thermodynamic analysis and experimental demonstration, and (2) anomalously abrupt kinetics in ferroelectric switching. We discovered the local chemical bonding environment and non-linear nucleation/domain growth competition in the switching process are key for the unique behaviors in wurtzite ferroelectrics. A developed model incorporating the nucleation – growth competition enables rational description of the anomaly in the observed switching kinetics. Those fundamental understandings on lattice dynamics in wurtzite ferroelectric materials provide insights on improving electromechanical coupling and controlling domain structure, which lead new device applications.