(Color online) (a) and (b) RHEED patterns for a 50 nm epitaxial NiTiSn film grown at 450 °C on MgO (001) showing a mixed domain surface reconstruction. The directions are referenced to the NiTiSn. (c) and (d) RHEED patterns for the MgO buffer layer, referenced to the MgO (001) crystal directions. (e) Model of NiTiSn on MgO (001) showing a 45° rotated cube-on-cube epitaxial relationship.
(a) XRD θ-2θ scan of a NiTiSn/MgO (001) film grown at 450 °C. (b) Full width at half maximum for the (002) and (004) NiTiSn peaks for samples grown at various temperatures. (c) Integrated area ratio of the (002) and (004) peaks as a function of growth temperature.
Temperature dependent resistivity, carrier density, and electron mobility for a 25 nm NiTiSn on MgO(001) sample with a 5 nm MgO cap.
SPELEEM micrographs and μLEED patterns during the anneal removal of an Sn cap from the NiTiSn surface. (a) Mirror electron mode image following a 400 °C anneal, and (b) x-ray photoemission image at the Sn 4d binding energy following a 400 °C anneal. (c) and (d) μLEED patterns for an exposed NiTiSn region and a Sn droplet region.
(Color online) (a)–(c) XPS core levels for a NiTiSn sample before the Sn cap, after the Sn cap, and after sputter removal of the Sn cap. The before cap spectra were measured in-situ using an Al Kα source (hν = 1486.6 eV). The Sn cap and sputter cleaned spectra were measured using synchrotron light with incident photon energies of 610 eV for Sn 3d, 980 eV for Ni 2p, and 580 for Ti 2p such that the kinetic energy was held roughly constant at 120 eV. (d) Integrated core level intensities as a function of sputter time.
Valence band spectrum after 20 min of argon sputtering using an incident photon energy of 70 eV. A broad shoulder of states is observed near the Fermi level (0 eV).
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