Strain-Controlled Formation Energy and Migration of Nitrogen Vacancy in Al1–x Sc x N: A First-Principles Study

The impact of strain on the formation energy and migration behavior of nitrogen vacancies (VNs) in Al1–x Sc x N has been investigated by first-principles calculations. The formation energy of VNs is obtained by total energy calculations. The migration barrier calculation utilizes the climbing nudged elastic band method. It is found that the formation energy of VNs is highly tunable with respect to the strain. The formation energy of VNs increases with the tensile strain increasing to +4% and decreases with the increasing compressive strain to −4%. A minimum formation energy of 4.11 eV is obtained when −4% strain is applied. Furthermore, the migration behavior of VNs is studied by calculating the migration barriers. Calculation results show that the migration barrier is strongly affected by strain. When the strain is −4%, the barrier is 2.46 eV while the barrier is increased to 2.71 eV under +4% strain. Therefore, a tensile strain can prevent the formation and migration of VNs. These findings suggest that strain engineering may serve as a tool for regulating VNs behavior in Al1–x Sc x N, potentially alleviating the ferroelectric degradations associated with VNs.