Observation of Self-Assembled Core–Shell Structures in Epitaxially Embedded TbErAs Nanoparticles

Self-assembled core–shell structured rare-earth nanoparticles (TbErAs) are observed in a III–V semiconductor host matrix (In0.53Ga0.47As) nominally lattice-matched to InP, grown via molecular beam epitaxy. Atom probe tomography demonstrates that the TbErAs nanoparticles have a core–shell structure, as seen both in the tomographic atom-by-atom reconstruction and concentration profiles. A simple thermodynamic model is created to determine when it is energetically favorable to have core–shell structures; the results strongly agree with the observations.