The Inversion Of Interfacial Potential For Metal/SiC And Its Application

Metal/SiC interface is an interesting and important issue for SiC devices applications. Theoretical studies in this field are mainly concentrated on ab initio calculations with simple interface models, while atomistic simulations are rather rare, which is due to the lack of related potentials.In this situation, we pay an effort to look for a systematic way to get interfacial potentials for metal/SiC system. First a pair-potential model is employed. By using a lattice inversion method, the interfacial pair potentials can be directly derived from ab initio adhesive energyies of some interfacial configurations. The obtained pontentials are parameter-free ones which are effective in a given phase space.However, they have limitations on transferability in modeling some other possible interface structures. In the view of charge distribution, the bonds between metal and SiC in the interface region have typical covalent character, which is responsible for the poor transferability of pair potentials. To improve it, SW three-body interactions are introduced as a modification, leading to a significantly better result than the pure two-body case.Based on the resultant interfacial potentials, atomistic simulations on interface structures and mechanical properties are carried out. For low metal coverage on SiC, deposition simulation is applied and the obtained patterns are quite consistent with experiments. And for high metal coverage, an atomic model with misfit dislocation is introduced. We find that there is a coherent interlayer on metal/SiC interface, and dislocation is above this layer. This is quite valuable for experimental check and first principle calculations. In addition, tensile test simulation is performed to study the mechanical properties of the interface. Since there is a strong adhesion between metal and SiC, the fracture takes place in the metal side, which may decrease the total tensile strength of the interface.Futher more, to gain insight in to the functional properties, an ab initio task is performed on alloy/SiC interfaces. It shows some interesting results on Schottky barrier height and interfacial adhesion, etc.