Defect Analysis of Rare‐Earth (Y, La, Sm) Oxide Doped AlN Ceramics for Electronic Device Applications

ABSTRACT Aluminum nitride (AlN) ceramics are widely used in high‐power electronic devices due to their excellent electrical insulation, high thermal conductivity, and chemical stability. Doping with rare‐earth oxides is a common modification method for AlN ceramics that enhances sintering behavior and thermal conductivity but simultaneously alters defect states, thereby affecting electrical properties. The evolution of these defects and their influence on electrical transport and heat conduction remain unclear. Herein, the defect behavior, electrical insulation, and thermal conduction of Y 2 O 3 , La 2 O 3 , and Sm 2 O 3 ‐doped AlN ceramics are systematically compared. A combination of direct current (DC) conductivity, electrochemical impedance spectroscopy (EIS), dielectric spectroscopy, and thermally stimulated depolarization current (TSDC) analyses confirms a pronounced defect “cleaning effect” induced by rare‐earth dopants, with an efficiency ranking of Sm > La > Y. The results reveal that oxygen substituting for nitrogen sites and aluminum vacancies dominate the low‐ and high‐temperature conduction processes, respectively. The influence of rare‐earth doping on thermal conductivity is also evaluated. Notably, the samples doped with 4 wt% Y 2 O 3 exhibit the best electrical insulation and the highest thermal conductivity. This work provides important insights into achieving synergistic optimization of the electrical and thermal properties of AlN ceramics through defect engineering.