Epitaxial growth of metals on (100) SrTiO3: The influence of lattice mismatch and reactivity

The model system Me/(100) SrTiO 3 (Me: Pd, Pt, Cu, Ni, Cr, Mo, Nb, and Al) was used to show that there exists a simple correlation between the formation of particular epitaxial orientations, the lattice mismatch between metal and SrTiO 3 , and the oxygen affinity of the metal. The growth of the metal films on the (100) SrTiO 3 surface was studied by reflection high-energy electron diffraction. Most metals (Pd, Pt, Ni, Nb and Al) grew with the following epitaxial orientation relationship on the SrTiO 3 : (100) SrTiO 3 ||(100) Me, [001] SrTiO 3 ||[001] Me. A second epitaxial orientation relationship was detected for Cr and Mo: (100) SrTiO 3 ||(100) Cr, Mo, [001] SrTiO 3 ||[011] Cr, Mo. For Mo, this orientation was detected only at very high growth temperatures. For each of the epitaxial orientation relationships, the substrate and film planes of four fold symmetry were parallel. Besides the second epitaxial orientation relationship, a third epitaxial orientation relationship was detected for Mo at growth temperatures below 900 K: (100) SrTiO 3 ||(110) Mo, [001] SrTiO 3 ||[001] Mo. In contrast to all other metals under investigation, Cu grew with a (111) fiber texture on the (100) SrTiO 3 surface. The appearance of the first two epitaxial orientation relationships can be interpreted with a simple relationship between the metals' oxygen affinities and the lattice mismatches with SrTiO 3 . This relationship can be used for other metals to predict epitaxy on the (100) SrTiO 3 surface.