Oxygen-defect engineering enabled high thermal conductivity in AlN ceramics at high temperature

Efficient thermal management is essential for ensuring the reliability and service lifetime of high-power electronic devices. As device power density and operating temperature continue to increase, maintaining efficient heat transport under elevated-temperature conditions has become increasingly important for advanced electronic packaging. However, despite substantial progress in improving the room-temperature thermal conductivity of AlN ceramics, studies on their thermal transport performance at elevated temperatures remain relatively limited. In this work, AlN ceramics with different Y 2 O 3 additions were fabricated by tape casting and pressureless sintering. The effects of Y 2 O 3 addition on oxygen impurity concentration, microstructure, thermal conductivity, mechanical properties, and defect characteristics were systematically investigated. The optimized 3Y sample exhibited a high thermal conductivity of 146 W/(m·K) at 150 ℃. Temperature-dependent dielectric spectroscopy was employed to investigate the relationship between oxygen-related defects and high-temperature thermal transport behavior. The results indicate that reduced oxygen-related defects effectively suppress defect-assisted phonon scattering, thereby improving thermal conductivity retention at elevated temperatures. This work provides new insight into oxygen impurity for developing high-performance AlN ceramic substrates for high-temperature thermal-management applications.