A comparing study on the evolution of Pd/Ni (1 0 0) and Pt/Ni(1 0 0) heteroepitaxial systems

Molecular dynamics simulations are performed to study the strain relief and the evolution of Pd/Ni(1 0 0) and Pt/Ni(1 0 0) heteroepitaxial systems by using embedded atom method. The atomistic mechanism for the formation of misfit dislocation in Pd/Ni(1 0 0) and Pt/Ni(1 0 0) epitaxial islands is analyzed by comparing the evolution behaviors of the two systems. The simulation results reveal that the strain of epitaxial islands due to lattice mismatch is released by the formation of misfit dislocations. However, the formation of misfit dislocations is different for the two systems. The formation of misfit dislocations in Pd islands is much easier than that in Pt islands. It is found that the positive solution heat of the alloy weakens the adhesion energy of heteroepitaxial system and facilitates the formation of misfit dislocations. The relative rigidity between the island and the substrate is also important for the formation of misfit dislocation, which can be related to the bulk modulus of the island.