Radiation-induced damage and static dielectric constant changes in AlGaN from multi-method simulations

This work presents a multiscale simulation study of irradiation induced amorphization and dielectric degradation in AlGaN alloys. Proton and alpha particle irradiation in Al x Ga 1-x N with different Al contents was first analyzed by Monte Carlo simulations to determine penetration depth, recoil energy transfer, vacancy production, and recoil atom distributions. These results were then used to guide molecular dynamics simulations of cumulative collision cascades, followed by core shell calculations of the static dielectric constant for pristine and damaged structures. The results show that increasing Al content extends the penetration depth of both incident particles, while alpha particles generate much stronger local recoil events, higher vacancy yields, and sharper damage peaks than protons. Successive cascades produce localized disordered channels and clear retention of non-wurtzite environments in all alloys. The disorder level exhibits a nonmonotonic composition dependence and reaches its maximum in Al 0.5 Ga 0.5 N. Higher temperature further promotes defect accumulation and stabilizes amorphous like structures. The static dielectric constants of damaged systems are consistently lower than those of defect free alloys, and the convergence of dielectric fluctuations becomes slower after irradiation. These changes originate from defect induced strain, coordination disruption, and weakened polar displacement correlations. The present results establish a direct link between ion energy deposition, structural disorder, and dielectric response in irradiated AlGaN.