Growth and characterization of epitaxial Mo/NbN superlattices

Epitaxial Mo/NbN superlattices were grown on MgO(001) substrates by reactive de magnetron sputtering. The epitaxial relationship between the bcc metal and the NaCl (B1)-structure compound is Mo(001) parallel to NbN(001), Mo[110]parallel to NbN[010], and the lattice mismatch is 1.4% given the 45 degrees rotation about the (001). Cross-sectional transmission electron microscope images show well-defined and relatively planar layers. High angle x-ray diffraction results show up to 25 superlattice reflections extending over approximate to 30 degrees in 2 theta. Kinematical model fits to the x-ray diffraction data suggest that the interface widths were only approximate to 0.3 nm, presumably because of the immiscibility of Mo and NbN. Initial nanoindentation results indicate hardness values of approximate to 28 GPa, about 3 times the rule-of-mixtures value. (C) 1996 American Institute of Physics.