Revealing the Defect‐Driven Ferroelectric Mechanisms of Aluminum Nitride

ABSTRACT Wurtzite III‐nitride compounds are CMOS‐compatible with widespread industrial interest to exercise ferroelectricity, despite their polar structure being highly resistant to polarization reversal. Here, we induce and tune ferroelectric properties in w‐AlN via direct‐write ion‐beam processing, using nanoscale patterned defect engineering as a post‐growth alternative to conventional cation substitution. Nanometric piezoresponse spectroscopy of the focused He + beam patterned defect concentrations in ferroelectric Al 0.92 B 0.08 N measures a localized 10x enhancement in effective piezoresponse and 40% reduction in switching barrier. The irradiation‐induced point defects convert piezoelectric AlN into a ferroelectric system with site‐saturated nucleation and raise the dielectric susceptibility, switched polarization, and effective piezoelectric coefficient. Enhanced defect‐lattice interactions in AlN increase carrier conduction and phonon scattering loss but preserve long‐range crystallinity. Based on atomistic analysis of nudged elastic band density functional theory calculations and reactive force field simulations, both nitrogen vacancies and defect complexes disrupt bond ordering, facilitating a line‐by‐line low‐barrier switching of pristine AlN.