Enhancing Electrical and Interfacial Properties of BeO/4H‐SiC Structures with SiO ₂ Interlayer

Abstract Beryllium oxide (BeO) has exceptionally high thermal conductivity (330 W m −1 ·K −1 ), a large bandgap energy, and a high dielectric constant, making it an optimal dielectric for high‐power devices. However, its direct application on 4H‐SiC is hindered by interfacial carbon‐cluster formation during high‐temperature annealing, primarily due to the decomposition of 4H‐SiC. In this study, a SiO 2 interlayer is introduced between BeO and 4H‐SiC using plasma‐enhanced chemical‐vapor deposition to address these challenges. Electrical measurements reveal that the BeO/SiO 2 /4H‐SiC stack exhibits a reduced leakage‐current density, an enhanced breakdown field (>7.5 MV cm −1 ), and a smaller capacitance–voltage hysteresis compared with direct BeO deposition owing to reduced interface defects. Band‐alignment analysis shows an increased conduction‐band offset between BeO/4H‐SiC, potentially contributing to improved carrier confinement. The interface trap density (Dit) is reduced by two orders of magnitude, indicating an improved interface quality owing to the presence of the SiO 2 interlayer. The SiO 2 interlayer significantly improves interface quality, reduces leakage current, and enhances the breakdown field of the BeO/4H‐SiC system. These results suggest that interfacial engineering using a SiO 2 interlayer can be an effective approach for improving the electrical reliability of high‐temperature dielectric stacks on 4H‐SiC.