Systematic approach to developing empirical potentials for compound semiconductors

Analytical bond-order potential for silver, palladium, ruthenium and iodine bulk diffusion in silicon carbide

The analytical bond-order potential has been developed for simulating fission product (Ag, Pd, Ru, and I) behavior in SiC, especially for their diffusion. We have proposed adding experimentally available elastic constants and physical properties of the elements as well as important defect formation energies calculated from density functional theory simulation to the list of typical properties as the extensive fitting database. The results from molecular dynamics simulations are in a reasonable agreement with defect properties and energy barriers of their experimental/computational counterparts. The successful validation of the new potential has established a good reliability and transferability of the potentials, which enables the ability of simulation in extended scale. The kinetic behavior such as diffusion of different interstitials is then realized by applying the new interatomic potentials. The bulk diffusion is less likely to dominate the transport of the four fission products under pure thermal condition, when we refer to their extremely small values of the effective diffusion coefficients. The interstitial mechanism is hard for Pd, Ru, and I to access due to the high formation energy and high migration energy. However, it is found that the migration energy of silver is relatively low, which indicates Ag diffusion via an interstitial mechanism being feasible, especially under irradiation condition, where massive interstitials can be formed in high-temperature nuclear reactors.

Atomistic study of misfit dislocation in metal/SiC(111) interfaces

The interatomic potentials across metal/SiC(111) interfaces are derived from ab initio adhesive energies by an inversion method. We use these potentials to investigate the structures, energies and Burgers vectors of misfit dislocations in metal/SiC(111) interfaces. Two kinds of interfacial dislocations are found in M/SiC(111) (M = Au, Ag, Al, Pt) interfaces, where the M/SiC(111) (M = Au, Al) system has partial dislocations and the M/SiC(111) (M = Ag, Pt) system has perfect dislocations. The former has a coherent interface while the latter corresponds to a semi-coherent interface.