Electronic properties of epitaxial TiN/VN(001) superlattices

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Abstract
Single‐crystal TiN/VN superlattices with layer thicknesses lTiN=lVN and period Λ ranging from 0.96 to 12.4 nm have been grown on MgO(001) substrates at 750 °C by reactive magnetron sputtering. The superlattice structures had uniform layer thicknesses as observed by cross‐sectional transmission electron microscopy and a comparison of x‐ray superlattice diffraction spectra with calculated spectra indicated that any interfacial mixing had to be less than ± three atomic layers, (i.e., <±0.6 nm). Electrical resistivity and Hall measurements carried out as a function of Λ showed that the room‐temperature electron carrier concentration n remained constant at 4.5×1022 cm−3 while the resistivity ρ increased and the electron mobility μ decreased rapidly with Λ2 V−1 s−1. The temperature coefficient of resistivity between 80 and 300 K decreased with decreasing Λ but remained positive (i.e., metallic). A modified quantum size effect model accounting for diffuse and specular scattering of electrons at superlattice interfaces was used to explain the electronic transport properties. Best fit results showed that the fraction of specularly scattered electrons was ∼0.3.