Brian M. Foley’s paper published in Applied Physics Letters – “Thermal conductivity of nano-grained SrTiO3 thin films”

Our paper – Foley et al., “Thermal conductivity of nano-grained SrTiO3 thin films” – was recently published in Applied Physics Letters (Appl. Phys. Lett. 101, 231908 (2012)). In this work, we measured the thermal conductivity of a series of SrTiO3 thin films with varying nanoscale grain sizes.  We found that the thermal conductivities of these films are well described by a model that accounts for the spectral, dispersive nature of phonon transport and the interplay between anharmonic Umklapp scattering and grain-boundary scattering.

Abstract

We measure the thermal conductivities of nano-grained strontium titanate (ng-SrTiO₃) films deposited on sapphire substrates via time-domain thermoreflectance. The 170 nm thick oxide films of varying grain-size were prepared from a chemical solution deposition process. We find that the thermal conductivity of ng-SrTiO₃ decreases with decreasing average grain size and attribute this to increased phonon scattering at grain boundaries. Our data are well described by a model that accounts for the spectral nature of anharmonic Umklapp scattering along with grain boundary scattering and scattering due to the film thickness.

This work was funded by NSF (CBET Award #1134311) and Sandia National Laboratories through the LDRD Program Office.