Ab initiostudy of the adsorption, migration, clustering, and reaction of palladium on the surface of silicon carbide

Abstract

This work presents first principle calculations to understand the adsorption, clustering, migration, and reaction of Pd on three different surfaces of 3C-SiC ({111}, {100} C-terminated, and {100} Si-terminated). The surfaces were chosen based upon experimental and theoretical work. Pd preferably binds to Si-terminated surfaces and has higher migration energies on these surfaces. Pd has low migration energies on non-Si-terminated surfaces facilitating the creation of Pd clusters. About 0.5 eV is gained per Pd atom added to a cluster. Reaction mechanisms are reported for Pd reacting on {100} surfaces. On the {100} C-terminated surfaces, a single Pd atom can substitute for a C with an energy barrier of 0.48 eV and two Pd atoms can substitute for two C atoms with an energy barrier of 0.04 eV. In both cases, the Pd atoms form Pd-C-C bridges between Si lattice sites. For the {100} Si-terminated surface, a single Pd atom can substitute for a Si atom with an energy barrier is 1.53 eV. No comparable low energy pathways were found on the {111} surface.