A thermodynamic and phase-field framework for domain nucleation and polarization switching in Al1− x Sc x N

Uniaxial wurtzite ferroelectrics have emerged as promising candidates for non-volatile memory applications; however, their large coercive fields remain a major challenge for device operation. Reducing the coercive field requires a fundamental understanding of the role of domain nucleation during polarization reversal, where polarization discontinuities at the domain walls are expected to strongly modify the nucleation energy barrier. Here, we develop a thermodynamic framework for inversion domain nucleation and polarization switching by combining classical nucleation theory with phase-field simulations. Using Al0.7Sc0.3N as a representative system, we demonstrate that the polarization discontinuity associated with inclined domain walls produces large local electrostatic potentials and electric fields, leading to high energy barriers for nucleation and highly anisotropic nucleation morphology. By explicitly incorporating electrostatic interactions among ionized dopants, electronic carriers, and bound charges arising from polarization discontinuities at domain walls, we find that the availability of free electronic carriers reduces the energy barrier for nucleation and brings the predicted coercive field closer to experimentally observed values and below dielectric breakdown limits. By explicitly incorporating the nucleation process, phase-field simulations capture the electric-field-driven evolution of domain nucleation and growth, enabling quantitative investigation of switching kinetics, providing a powerful approach for understanding and predicting polarization-switching behavior and long-term reliability in ferroelectric memory devices.