Tuning lattice thermal conductance by porosity control in ultrascaled Si and Ge nanowires Available to Purchase

Porous nanowires (NWs) with tunable thermal conductance are examined as a candidate for thermoelectric devices with high efficiency. Thermal conductance $(σl)$ of porous NWs is calculated using the phonon dispersion obtained from a modified valence force field model. Porosity in the NWs break the crystal symmetry leading to the reduction in ballistic $σl$⁠. [100] Si and Ge NWs show similar percentage reductions in $σl$ for the same amount of porosity. The model predicts an anisotropic reduction in $σl$ in SiNWs, with [111] showing the maximum reduction followed by [100] and [110] for a similar hole radius. The reduction in $σl$ is attributed to phonon localization and anisotropic mode reduction.