Temperature-dependent thermal conductivity of nanoporous Bi thin films by controlling pore size and porosity

Abstract

We have recently reported that 2D nanoporous Bi thin films have a thermal conductivity that is similar to 6 times smaller than that of the bulk materials at room temperature. Extending from this, we further realized the significance of temperature dependence of thermal conductivity in nanoporous Bi thin films. Therefore, in this study we investigate the thermal conductivities of 50-nm-thick thin films with film porosities in the 20-300 K temperature range. The behavior on the temperature-dependent thermal transport can be quantitatively explained by enhanced phonon scattering. Furthermore, our experimental and calculated results confirmed that the porosity rather than the pore size of nanoporous Bi thin films does indeed play a strong effect in the reduction of their thermal conductivities. (C) 2015 Elsevier B. V. All rights reserved.