Thermal conductance of epitaxial interfaces

Abstract

The thermal conductance of interfaces between epitaxial TiN and single crystal oxides is measured at temperatures between 79.4 and 294 K using time-domain thermoreflectance. The analysis method relies on the ratio of the in-phase and out-of-phase signals of the lock-in amplifier for more accurate data analysis. The validity of this approach is tested by measurements on 6.5, 11.8, and 25 nm thick thermally oxidized ${\mathrm{SiO}}_{2}$ on Si. The thermal conductances G of TiN/MgO(001), TiN/MgO(111), and ${\mathrm{T}\mathrm{i}\mathrm{N}/\mathrm{A}\mathrm{l}}_{2}{\mathrm{O}}_{3}(0001)$ interfaces are essentially identical and in good agreement with the predictions of lattice dynamics models and the diffuse mismatch model with a four-atom fcc unit cell. Near room temperature, $G\ensuremath{\approx}700{\phantom{\rule{0ex}{0ex}}\mathrm{M}\mathrm{W}\mathrm{m}}^{\ensuremath{-}2}\phantom{\rule{0ex}{0ex}}{\mathrm{K}}^{\ensuremath{-}1},$ $\ensuremath{\approx}5$ times larger than the highest values reported previously for any individual interface.