The structural, electronic, and adhesive properties of the $4\text{H-SiC}\left(0001\right)/{\text{Ti}}_3{\text{SiC}}_2\left(0001\right)$ interface are systematically investigated by first-principles calculations. A total of 96 candidate interface geometries are considered, encompassing four SiC terminations, each of which involves six ${\text{Ti}}_3{\text{SiC}}_2$ terminations and four stacking sequences. We find that the fundamental influence of the SiC substrate on the optimal Si-terminated interface is twofold characterized atomically by pulling the interfacial C atoms of ${\text{Ti}}_3{\text{SiC}}_2$ toward the positions that would normally be filled by C in bulk SiC and electronically by forcing the density of states projected on the interfacial C of ${\text{Ti}}_3{\text{SiC}}_2$ to approach that of C in bulk SiC rather than bulk ${\text{Ti}}_3{\text{SiC}}_2$. Consequently, the interfacial C of ${\text{Ti}}_3{\text{SiC}}_2$ is reasonably viewed as a natural extension of the C sublattice of bulk SiC across the interface. In contrast, atomic relaxation in the optimal C-terminated interface results in minor rearrangement, wherein the interfacial C of ${\text{Ti}}_3{\text{SiC}}_2$ rests straight above interfacial C of SiC. Regardless of the relaxation and SiC terminations, adhesion is found to be sensitive to choice of ${\text{Ti}}_3{\text{SiC}}_2$ termination and interfacial C to be an important factor influencing adhesion strength. Using several analytic techniques, we have characterized the electronic structures thoroughly and determined the interfacial bonding to be of a mixed covalent-ionic nature.

• Received 26 November 2008

DOI:https://doi.org/10.1103/PhysRevB.79.045318