Adhesion and electronic properties of 4H-SiC/α-Al2O3 interfaces with different terminations calculated via first-principles methods

To comprehensively reveal the microscopic properties of the 4H-SiC/α-Al2O3 interface, not only the properties of 4H-SiC and α-Al2O3 surfaces, but also the interface separation work, interface energies, band offsets, charge transfer, interfacial bonding, and partial density of states for different types of 4H-SiC/α-Al2O3 interfaces were studied using the first-principles method. Considering the two distinct crystal faces of 4H-SiC (Si-terminated and C-terminated surfaces) and the three distinct terminal configurations on the α-Al2O3 side (single Al (Al1-terminated), double Al (Al2-terminated), and O-terminated surface), we built six different types SiC/Al2O3 interfaces (Si-Al1, Si-Al2, Si-O, C-Al1, C-Al2, and C-O interfaces). The results of the interface separation work for the O-terminated interfaces (Si-O and C-O interfaces) revealed that the O-terminated interfaces were significantly greater compared to Al1- and Al2-terminated interfaces, indicating the pronounced dominance of O-terminated interfaces in terms of bonding strength across the six interfacial structures. Moreover, the charge transfer, interfacial bonding, and electronic properties for the interfaces showed that the O-terminated interfaces had larger charge transfer and more interfacial bonds. Additionally, the larger charge transfer at the O-terminated (especially Si-O interface) interfaces caused the larger conduction band offsets (CBOs), which could effectively prevent leakage current and improve the reliability of SiC/Al2O3 devices.